Giant Parotid Pleomorphic Adenoma with Atypical...

Case ReportGiant Parotid Pleomorphic Adenoma with Atypical HistologicalPresentation and Long-Term Recurrence-Free Follow-Up afterSurgery: A Case Report and Review of the Literature

Mohammed AlKindi ,1 Sundar Ramalingam ,1 Lujain Abdulmajeed Hakeem ,1

and Manal A. AlSheddi 2

1Department of Oral and Maxillofacial Surgery, College of Dentistry, King Saud University, Riyadh, Saudi Arabia2Department of Basic Sciences, College of Dentistry, Princess Nourah Bint Abdulrahman University, Riyadh, Saudi Arabia

Correspondence should be addressed to Sundar Ramalingam; [email protected]

Received 5 July 2020; Revised 14 August 2020; Accepted 21 August 2020; Published 1 September 2020

Academic Editor: Pravinkumar G. Patil

Copyright © 2020 Mohammed AlKindi et al. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work isproperly cited.

Salivary gland tumors (SGT) comprise 3% of all head and neck tumors, are mostly benign, and arise frequently in the parotid gland.Pleomorphic adenoma (PA) is the commonest SGT, representing 60-70% of all benign parotid tumors. Clinically, parotid PApresents as irregular, lobulated, asymptomatic, slow-growing preauricular mass, involving both superficial and deep lobes, andcould grow to gigantic proportions. Histologically, PA has epithelial and mesenchymal elements in chondromyxoid matrix andis managed surgically. Based on a review of 43 cases reported in English literature since 1995, giant parotid PA is reported aslarge as 35 cm (diameter) and 7.3 kg (resected weight). Although rare, 10 cases of malignant transformation were reported in thereview. Surgical management included extracapsular dissection (ECD), superficial parotidectomy, and total parotidectomy forbenign tumors, and adjuvant radiation or chemotherapy for malignant tumors. We further present the case of a 36-year-oldhealthy male with slow-growing and asymptomatic giant parotid PA, of 4-year duration. The patient presented with firm,lobulated preauricular swelling, provisionally diagnosed as PA based on radiographic and cytological findings. The tumor wasresected through ECD, and the patient had uneventful postoperative recovery and a 7-year recurrence-free follow-up period.Histological examination revealed epimyoepithelial proliferation punctuated by chondromyxoid areas, with extensive squamousmetaplasia and keratin cysts. To the best of knowledge from indexed literature, giant parotid PA is rarely reported in SaudiArabia. In addition to its rarity, this case is reported for its benign nature despite atypical histological presentation, successfulsurgical management without complications, and long-term recurrence-free follow-up. Based on this report, clinicians must beaware of atypical histological presentations associated with PA and plan suitable surgical management and follow-up to avoidmorbidity. Nevertheless, attempts must be made to diagnose and manage these lesions at an early stage and before they reachgigantic proportions.

1. Introduction

Neoplastic lesions of the salivary glands are uncommon andcomprise less than 3% of all reported head and neck tumors[1, 2]. Nearly 80% of the reported salivary gland tumors(SGT) are benign and occur predominantly in major salivaryglands, with the parotid gland being the commonest site (70–80%) [2, 3]. Often presenting as slow-growing, painlessmasses, tumors involving major salivary glands are rarely

aggressive or malignant (<10%). On the contrary, tumors ofminor salivary glands while occurring rarely have a prepon-derance to be malignant (80–90%) [2, 3]. Pleomorphic ade-noma (PA) is the commonest SGT, accounting for almost60–80% of all benign SGT and 60–70% of all parotid glandtumors [1, 3]. Clinically, PA presents as an irregular, rubbery,lobulated, slow-growing mass without any associated pain ordiscomfort. The presenting complaint is typically related tounpleasant or unesthetic facial appearance, which when

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https://doi.org/10.1155/2020/8828775

disregarded can lead to patients reporting with huge lesions[4]. Reports in the literature suggest resected dimensions ofPA to be frequently in the range of 2 cm to 6 cm and rarelyreaching even up to 25–35 cm [4, 5].

As the name suggests, PA is histologically categorized as abenign mixed (pleomorphic) tumor of ductal and myoe-pithelial cell origin. Owing to the pluripotential nature ofmyoepithelial cells, the tumor is composed of epithelial andfibrous, myxoid, and cartilaginous mesenchymal elementssurrounded by a pseudocapsule, with occasional squamousmetaplasia [3, 4, 6]. While the diagnosis of PA is based pri-marily on clinical and histological findings, the mainstay ofmanagement is by surgical excision [1, 4]. Depending upontheir size and depth of involvement, parotid PA is surgicallymanaged either by superficial parotidectomy (SP), extracap-sular dissection (ECD), or total parotidectomy (TP). All ofthe above procedures carry the risk of postoperative facialnerve paralysis and Frey’s syndrome [1, 7]. Recurrence isusually associated with inadequate clearance and incompleteremoval of pseudocapsule, and malignant transformation hasbeen reported with large, long-standing PA [4, 7].

Although uncommon, giant pleomorphic adenomas ofthe parotid gland have been reported. An electronic searchof the English-language articles through the Medline, Scopus,and Google Scholar databases revealed 43 reports of giantparotid PA since 1995 [4, 8–32], with sizes ranging up to28-33 cm [15, 18, 27] and tumor mass ranging up to 6.85–7.3 kg [10, 27]. Major reasons for patients reporting withlarge PA are lack of resources, inaccessibility to medical facil-ities, fear of surgical procedure, and poor awareness, com-pounded by an asymptomatic and slow-growing lesion [4].The aim of this paper is to add to the existing scientific liter-ature, a case of giant parotid PA treated surgically by ECD,followed by uneventful postoperative recovery and a 7-yearrecurrence-free follow-up. This paper also attempts to high-light the benign nature of parotid PA, despite the atypicalhistological presentation, which could be associated with it.

2. Case Report

A 36-year-old healthy male patient reported to the oraland maxillofacial surgery outpatient clinic at the Collegeof Dentistry and Dental University Hospital, King SaudUniversity, in October 2012. The patient sought medicalattention for a slow-growing, painless swelling in the rightpreauricular region. History revealed that the patientnoticed the swelling almost 4 years ago, and since then,it had gradually increased in size with no obvious symp-toms or changes to the overlying skin. Upon interviewing,the patient reported no relevant medical or surgical historyand mentioned fear of surgery and absence of discomfortas reasons for delaying medical consultation, in spite ofan unesthetic facial appearance.

Clinical examination revealed a firm, nontender, nodular,and mobile swelling with apparently normal overlying skin.The swelling extended superoinferiorly from the level of theexternal ear to the lower border of the mandible and antero-posteriorly from the angle of the mouth to the posterior bor-der of the mandible. There was no lymph node involvement

or facial nerve deficit (Figure 1). Preoperative computedtomography (CT), magnetic resonance imaging (MRI), andfine-needle aspiration cytology (FNAC) were ordered. CTwith contrast revealed a well-defined mass lesion in thesuperficial lobe of the right parotid gland, without any under-lying bony erosion and normal-appearing pharynx, larynx,and parapharyngeal spaces. While confirming the CT find-ings, head and neckMRI further demonstrated a well-demar-cated, heterogeneous, mass lesion measuring 10 × 7 × 8 cm inmaximum dimension (Figure 2). FNAC showed numerousscattered groups and clusters of plasmacytoid myoepithelialcells, associated with a chondromyxoid matrix. A provisionaldiagnosis of PA with no malignant tendency was arrived atbased on CT, MRI, and FNAC findings.

Surgical removal of the right parotid SGT under generalanesthesia was planned and explained to the patient. Follow-ing informed consent, the lesion was excised completelythrough ECD, with preservation of all branches of the facialnerve. The right parotid gland was approached using a cervi-cally extended preauricular skin incision. A clearly discern-ible plane of dissection around the tumor was used fordissecting the tumor mass, without any iatrogenic damageto the facial nerve branches. Owing to the long-standingnature, multiple small feeder vessels had to be ligated circum-ferentially around the tumor to achieve hemostasis. Theintraoperative period was unremarkable, and the patientdid not require any blood transfusions (Figure 3). Theresected mass was bilobed and ovoid in shape with a finaldimension of 7 × 13 × 7 cm and weighing 1.2 kg.

Histopathological examination of the excised specimengave a gross appearance of a partially encapsulated mass con-taining myoepithelial and ductal proliferation. There wasmarked stromal hyalinization, squamous metaplasia, andkeratinization. Some epithelial islands exhibited papillaryconfiguration, along with large cysts and inflammation.Chondromyxoid changes and fibrosis were evident through-out the tumor. Certain foci of tumor islands were seenapproaching and breaking through it. Hematoxylin and eosin(H&E) stained sections revealed a partially encapsulatedtumor with variable histopathological features and focaleffacement of the fibrous capsule. The tumor typicallyshowed epithelial/myoepithelial proliferation punctuated bychondromyxoid areas. Aggregates of plasmacytoid myoe-pithelial cells as well as ducal differentiation surrounded byclear myoepithelial cells were evident. Based on the abovefindings, a final diagnosis of benign PA was reached. Whilethe tumor sections showed no evidence of malignant change,there was extensive squamous metaplasia and keratin cystformation, which were atypical for PA (Figure 4). The patientwas therefore advised close follow-up, once every month forthe first year postoperatively and subsequently once in sixmonths.

At 6 weeks postsurgery, the patient had unremarkablewound healing without any neurological deficit of the facialnerve (Figure 5). As of December 2019, the patient had arecurrence-free follow-up period of 7 years and presentedwith normal activity of muscles of facial expression, indicat-ing the absence of any long-term facial nerve weakness(Figure 6).

2 Case Reports in Dentistry

3. Discussion

The parotid gland is the largest salivary gland with an averageweight ranging from 0.015 to 0.021kg and measuring approx-imately 5:8 × 3:4 cm in the craniocaudal and ventrodorsaldimensions, respectively. Being the first salivary gland to

develop in utero, during the 6th gestational week, it is anatom-ically located bilaterally between the mastoid process oftemporal bone and ramus of the mandible. The terminalbranches of the facial nerve are an important anatomic land-mark which divide the parotid gland into its superficial anddeep lobes [33]. Although SGT are uncommon, they are

(a) (b)

Figure 1: Preoperative clinical photograph of the right preauricular swelling. (a) Right lateral facial view shows the swelling extendingsuperoinferiorly from a point anterior to the helix of the external ear until the lower border of the mandible; anteroposteriorly, theswelling is seen extending from the angle of the mouth to the posterior border of the mandible; the ear lobe is deflected outward andelevated, and the skin overlying the swelling appears free of any ulceration, puckering, or discharge. (b) Frontal facial view shows theswelling causing facial asymmetry and obliterating the view of most of the right external ear; there is no clinical evidence of facial nerveweakness or deficit.

R

(a)

R

(b)

Figure 2: Preoperative radiographic examination of the right preauricular swelling. (a) Contrast-enhanced computed tomography axialsection at the level of mandibular teeth shows a well-defined mass lesion in the superficial lobe of the right parotid gland, without anyunderlying bony erosion and normal-appearing pharynx, larynx, and parapharyngeal spaces. (b) Magnetic resonance imaging coronalsection along the posterior border of the mandible shows a large, heterogeneous, well-demarcated solid mass lesion within the rightparotid superficial lobe and measuring 10 × 7 × 8 cm at maximum dimensions.

3Case Reports in Dentistry

predominantly benign and are reported frequently in theparotid gland [2]. The present report details a case of giantPA in the right parotid gland, along with its surgical manage-ment, histological presentation, and long-term recurrence-freefollow-up.

Pleomorphic adenoma is the commonest mixed SGTarising in the parotid gland, and several cases have beenreported in the literature. Although there are no specificphysical criteria outlined in the literature to classify giantparotid PA, the earliest recorded case report dates back to1863 [27]. In this report, Spence reported a mixed tumorinvolving lateral face and neck and a resected mass weighinggreater than 1 kg [27]. Similarly, Short and Pullar (1956)reviewed and reported a case of giant parotid PA weighingabout 2.3 kg [27]. In a report reviewing 31 cases of giantparotid PA over a period of 140 years by Schultz-Coulon,the resected tumor weights ranged from 1.0 to 26.50 kg, witha greater female predilection (64.5%) and only 3 cases ofmalignant transformation [15]. Based on a review of the 10

largest parotid PA published between 1863 and 1994, Buent-ing et al. reported resected tumors ranging in weight from2.83 to 26.50 kg, in patients with age ranging from 25 to 85years and 90% female predilection [10].

A literature search was conducted to review giant parotidPA cases reported in Medline, Scopus, and Google Scholardatabases. The search strategy involved a combination ofsearch keywords including “GIANT”, “PAROTID GLAND”,and “PLEOMORPHIC ADENOMA”, based on which 288articles were identified from the three databases (Med-line—66; Scopus—63; Google Scholar—159). Reviewingtheir abstracts, articles published in English only wereselected based on them reporting a case or series of cases ofgiant parotid PA, including clinical, radiographic, histologi-cal, and surgical outcomes. Twenty-six articles published inEnglish language were identified [4, 8–32] since 1995, andthey reported 43 cases of PA in total. While most of the arti-cles selected for review were single case reports, three articleswere case series reporting about two cases [16], three cases

(a) (b)

Figure 3: Intraoperative photograph showing (a) the surgical plane for extracapsular dissection of the right parotid tumor and (b) the excisedtumor specimen.

500 𝜇m

(a)

200 𝜇m

(b)

Figure 4: Histological examination of the excised tumor specimen showing (a) a partially encapsulated mass lesion containing myoepithelialand ductal proliferation, with stromal hyalinization, squamous metaplasia, and keratinization; epithelial islands exhibiting papillaryconfiguration, large cysts surrounded by inflammation, focal areas of chondromyxoid changes and fibrosis, and tumor islandsapproaching and penetrating the capsule are evident (HE original magnification ×4); (b) extensive squamous metaplasia and keratin cystformation are conspicuous at higher magnification (HE original magnification ×10).


[17], and 15 cases [32], respectively. The largest case series inthe present review, comprising 15 PA patients, was reportedby Pareek et al. [32].

Although majority of the reported cases were in patientsaged 45 years or older (n = 30, 69.8%), the age at clinical pre-sentation and surgery ranged from 21 to 92 years. Theasymptomatic, slow-growing nature of pleomorphic ade-noma was evidenced by the fact that the duration from thefirst observation of lesion to reporting for treatment variedfrom 5 to 35 years. Demographically, there were morefemales (n = 25, 58.1%) than males, and all reported caseswere unilateral, with the right side (n = 23, 53.5%) affectedmore than the left. In terms of clinical dimension, the tumorsranged from 3 to 5 cm in diameter [16, 17], until 35 × 28 cm[27], in two perpendicular planes. The clinical dimensionscorroborated with the resected tumor weight, wherein thesmallest tumor weighed 0.12 kg [16] and the largest weighed7.3 kg [27]. Predominant clinical presentation of the tumorswas that of a large, lobulated, and pedunculated mass withapparently normal overlying skin. Ulceration of the skinwas reported in eight patients, out of which five were report-edly associated with malignant change [15, 23, 24, 30, 32],and the remaining three were due to injury [18, 29, 32]. Ana-tomically, the tumor more commonly involved the superfi-cial lobe of the parotid gland (n = 29, 70.7%) giving rise tothe clinical presentation of a large preauricular mass. Never-theless, when the deep lobe of parotid and parapharyngealspaces were involved by the tumor, patients presented withan intraoral swelling leading to soft palate displacement, dif-ficulty in swallowing and breathing, and obstructive sleepapnea [11, 13, 16, 17, 22, 25]. While diagnosis was primarilybased on clinical and radiographic (USG, CT, andMRI) find-ings, preoperative diagnosis was established through FNAC

in most cases. The clinical, radiographic, surgical, and histo-logical findings in the reviewed case reports are detailed inTable 1.

Preoperative diagnosis of PA is routinely based on clini-cal findings, supplemented by radiological investigationssuch as CT, MRI, and USG [2]. The role of FNAC in arrivingat a provisional diagnosis has been debated and considerednonrepresentative due to varying histological patterns at dif-ferent sites within the same tumor [34]. In terms of histo-pathological diagnosis, the characteristic feature of PA is itshistological diversity and differing arrangements of epithelialand mesenchymal tissue elements. Das and Anim [34], basedon a study comparing FNAC and histological sections in PA,reported consistent findings of epithelial cells in a myxoidstroma through cytological and histological examination.Nevertheless, they reported better characterization of onco-cytic changes such as acini, giant cell and mucus globule for-mation, and squamous and chondroid metaplasia inhistological sections [34]. Preoperative diagnosis of PA inthe present case was based on a combination of clinicalexamination, radiographic investigations, and FNAC. Ourradiographic finding (CT and MRI) of well-demarcated, lob-ulated, and heterogeneous mass lesion involving the parotidgland and FNAC finding of plasmacytoid epithelial cells ina chondromyxoid matrix were in coherence with the major-ity of cases reported in the review (Table 1). Additionally,necrotic changes [10, 24, 30] and calcifications [4, 30], withinthe tumor, have also been reported in the literature, based onCT and in association with malignant change [24, 30]. Thecombination of CT and MRI enables optimum preoperativediagnosis of pleomorphic adenomas and precise planningof the surgical approach for tumor resection [11]. In additionto volumetric information, CT with contrast provides

(a) (b)

Figure 5: Postoperative clinical photograph taken 6 weeks postsurgery. (a) Lateral facial view shows healing surgical incision without anyobvious postoperative sequelae. (b) Symmetric facial appearance observed in the frontal facial view, with no clinical weakness of musclesof facial expression.


knowledge about vascularity of the tumor andMRI shows therelationship of the tumor to surrounding vital structures inthe head and neck regions [11].

The treatment of PA irrespective of their size, severity, ormalignant potential is only by surgery. Based on our litera-

ture review, giant PA involving the superficial lobe of parotidwas managed either by SP or ECD [4, 10, 24, 26–29, 31, 32].On the contrary, TP was reportedly done for tumors exhibit-ing malignant characteristics [8, 12, 15, 17, 19, 20, 23, 30] andthose involving both the deep and superficial lobes [9, 13, 14,

(a) (b)

(c) (d)

(e)

Figure 6: Postoperative clinical photograph taken 7 years postsurgery with facial gestures eliciting unrestrained action of different muscles offacial expression. (a) Unremarkable healing of the surgical wound without any scarring and the patient is seen smiling. (b) Frontal facial viewshowing symmetric appearance and the patient is seen puffing the cheeks. (c, d) Bilateral symmetric eyelid closure and opening. (e) Thepatient is seen grinning broadly.


Table1:Reviewof

giantparotidpleomorph

icadenom

acase

repo

rtsandtheirdemograph

ic,clin

ical,radiographic,surgical,and

histologicalfind

ings.

Autho

r(year)

Patient

demograph

ics

Preop

erativeevaluation

Surgicalintervention

Postoperative

period

Age

(in

years)/gender

Duration

oflesion

Affected

side

Clin

ical

dimension

Clin

ical

presentation

Investigations

Procedu

reResected

dimension

Reasonfor

surgery

Histologicalfi

ndings

Postoperative

course

Follow-up

Alvarez-C

añas

andRod

illa

(1996)

[8]

86/F

15years

Left

Largepainless

preauricular

mass

which

enlarged

sudd

enlyover

the

past1year

and

associated

with

facialnervedeficit

Onlyclinical

exam

ination

Totalparotidectom

y9:5

×8×

7cm

Sudd

enincrease

insize

with

facialnerve

deficit

Mixed

malignant

transformationof

PAwithsalivary

ductalcarcinom

aandhigh-grade

fibrosarcomaelem

ents

Patient

developedlocal

recurrence

oftumor

anddied

6mon

thsafter

surgery

Lomeo

(1996)

[9]

74/F

35years

Left

Largepreauricular

mass

Onlyclinical

exam

ination

Totalparotidectom

y

Patient

was

convincedfor

surgeryby

grandchildren

Pleom

orph

icadenom

a

Buentingetal.

(1998)

[10]

85/F

20years

Right

Large,multino

dular

preauricular

mass

withevidence

ofinfection.

The

mass

was

tenselycystic

andhadprom

inent

veinsnear

thebase

CTshow

eda

parotidmass14

cmacross

with

extensivenecrotic

fociandnu

merou

sfeedingvessels,

which

wereno

tam

enableto

embo

lization

Extracapsular

dissection

ofthe

tumor

mass

26cm

diam

eter

(6.85kg)

Inadvertent

injury

tothe

base

ofthemass

resulting

inbleeding

and

infection

Pleom

orph

icadenom

awithextensive

necrosisand

cartilagino

usmetaplasia

1-year

recurrence-free

follow-up

Rod

riguez-

Ciurana

etal.

(2000)

[11]

48/F

30years

Right

Largemassin

the

subm

andibu

larand

laterocervical

region

s,extend

ing

intraorally

from

soft-palateto

floo

rof

mou

th

MRIshow

edamass

involvingthedeep

lobe

oftheparotid

gland,

extend

ing

into

paraph

aryngeal,

prestyloid,and

subm

andibu

lar

spaces,d

isplacing

externaland

internalcarotid

arteries

and

thinning

theramus

ofmandible.

Measuring

6×5×

4cm

.FNACwas

indicative

ofPA

Deeplobe

parotidectom

ythroughcervical

transparotid

approach

Pleom

orph

icadenom

a

Transient

facial

nerveweakn

ess

for4weeks

Manuel(2002)

[12]

68/F

Left

Recurrent

parotid

masswhich

was

incompletely

excisedearlierand

diagno

sedas

mixed

malignant

tumor

Total

parotidectom

y,with

removalof

facial

nervebranches

due

totumor

infiltration

andmod

ified

neck

dissection

Recurrent

lesion

inthepreviously

excisedtumor

site

Carcino

sarcom

aarising

from

PA,w

ithresidu

alPA,epimyoepithelial

carcinom

a,and

pleomorph

icsarcom

a.Multiplemetastatic

cervicallymph

nodes

Patient

was

operated

for

metastatic

anterior

chest

wallm

ass,7

mon

ths

postsurgeryand

hadan

18-

mon

thdisease-

free

follow-up


Table1:Con

tinu

ed.

Autho

r(year)

Patient

demograph

ics

Preop

erativeevaluation


Postoperative

period

Age

(in

years)/gender

Duration

oflesion

Affected

side

Clin

ical

dimension

Clin

ical

presentation

Investigations

Procedu

reResected

dimension

Reasonfor

surgery

Histologicalfi

ndings

Postoperative

course

Follow-up

Panou

ssop

oulos

etal.(2002)[13]

63/M

30years

Left

13×12

cm

Large,lobu

lated

massin

the

subm

andibu

lar,

preauricular,and

laterocervical

region

s,extend

ing

intraorally

tothe

lateralp

haryngeal

wallatthelevel

oftongue

MRIshow

edawell-

definedmass

involvingbo

thsuperficialanddeep

lobesof

theparotid

gland,

and

extend

inginto

the

paraph

aryngeal

space,displacing

tissuesdeep

tothetonsil

Totalparotidectom

ythroughcervical

transparotid

approach

Pleom

orph

icadenom

a

deSilvaetal.

(2004)

[14]

76/M

>30years

Left

20×30

cm

Large,oval

preauricular

swellin

g,firm

inconsistency,

withveno

usengorgem

enton

overlyingskin

andmovable

FNACwas

indicative

ofPA

Totalparotidectom

ywithpreservation

offacialnerve

20×14

×12

cm(3.5kg)

Pleom

orph

icadenom

a

Facialnerve

deficitobserved

1week

postop

eratively

andrecovered

90%

by1mon

th

1-year

recurrence-free

follow-upand

complete

recovery

offacialnerve

function

Hon

daetal.

(2005)

[15]

72/F

20years

Left

Large,pedu

nculated

preauricular

mass

extend

ingup

tothe

subm

andibu

lar

region

,witha

historyof

rapid

grow

thin

preceding

3mon

thsand2

areasof

ulceration

withyellowish,

foul-

smellin

gdischarge

inthelower

partof

themass.An

associated

anterior

chestwallm

ass

measuring

10×8

cmwas

clinically

identified

CTshow

edamass

withmultiple

encapsulated

nodu

lesinvolving

theentire

parotid

gland,

having

severalfeeder

vesselsandsupp

lied

predom

inantly

bythetransverse

facial

artery.C

oincidental

find

ingof

abno

rmal

skullb

aselesion

measuring

4cm

indiam

eter.C

hest

radiograph

revealed

multiplemetastatic

nodu

les,measuring

arou

nd1cm

,in

both

lungs

Totalparotidectom

y+simultaneou

sresectionof

anterior

chestwallm

ass

33×18

×17:5cm

exop

hytictumor

(6.051

kg)

Sudd

enincrease

insize

with

ulceration

and

discharge

Pleom

orph

icadenom

awithfocalareas

ofmalignant

adenocarcino

macells

withhyperchrom

atic

nucleiandincreased

mitoticfigures.Similar

histologicalfind

ings

observed

intheresected

anterior

chestwallm

ass

Patient

died

6mon

ths

postsurgery,

dueto

metastaticlung

disease


Table1:Con

tinu

ed.

Autho

r(year)

Patient

demograph

ics

Preop

erativeevaluation


Postoperative

period

Age

(in

years)/gender

Duration

oflesion

Affected

side

Clin

ical

dimension

Clin

ical

presentation

Investigations

Procedu

reResected

dimension

Reasonfor

surgery

Histologicalfi

ndings

Postoperative

course

Follow-up

Ruiz-Laza

etal.

(2006)

[16]

54/M

5years

Left

3cm

Solid

massin

preauricular

and

mandibu

larangle

region

s

MRIshow

eda

multilobu

latedmass

measuring

8cm

indiam

eter

and

extend

ingfrom

deep

lobe

ofthe

parotidglandinto

paraph

aryngeal

space,displacing

the

pharyngealairw

aymedially

andthe

jugularandcarotid

vesselspo

steriorly.

FNACwas

indicative

ofPA

Totalparotidectom

ythroughcervical

transparotid

approach

and

facialnerve

preservation

Pleom

orph

icadenom

a

Postoperative

facialnerve

deficitwhich

recovered

completelyin

6mon

ths

3-year

recurrence-free

follow-up

Ruiz-Laza

etal.

(2006)

[16]

21/M

Right

Intraoralm

ass

occupyingtheentire

softpalatewithno

otherassociated

symptom

s

MRIshow

edawell-

definedmasslesion

measuring

6×5×

4cm

inthe

paraph

aryngeal

spaceandwith

apparent

continuity

tothedeep

lobe

oftheparotidgland.

FNACwas

indicative

ofPA

Surgicalexcision

oftumor

masson

ly,

throughintraoral

approach

and

“Dou

ble-Y”incision

insoftpalate

11×10

cm(0.12kg)

Pleom

orph

icadenom

a

3-year

recurrence-free

follow-up

Sergi etal.

(2008)

[17]

36/M

1year

Left

5cm

Solid

preauricular

mass

USG

show

edtwo

hypo

echo

genic,

lobu

latedmasses

measuring

2:5×1:9

×1:6

cminthedeep

lobe

oftheparotid

glandand4:4×

5:1×4:6c

mpo

sterior

tomandibu

lar

ramus.M

RI

revealed

expansive

massmeasuring

abou

t5cm

inthe

deep

lobe

ofthe

parotidgland,

extend

ingfrom

mandibu

larangleto

lateralp

haryngeal

wallm

edially

Using

cervical

transparotid

approach,

superficialanddeep

lobe

parotidectom

yperformed

separatelyto

preserve

facial

nervebranches

Pleom

orph

icadenom

a

Transient

neurological

deficitof

marginal

mandibu

lar

branch

offacialnerve


Table1:Con

tinu

ed.

Autho

r(year)

Patient

demograph

ics

Preop

erativeevaluation


Postoperative

period

Age

(in

years)/gender

Duration

oflesion

Affected

side

Clin

ical

dimension

Clin

ical

presentation

Investigations

Procedu

reResected

dimension

Reasonfor

surgery

Histologicalfi

ndings

Postoperative

course

Follow-up

Sergietal.

(2008)

[17]

42/M

Right

3cm

Solid

preauricular

mass

MRIshow

edamass

inthedeep

lobe

oftheparotidgland,

extend

inginto

paraph

aryngeal

spaceanddisplacing

theph

aryngeal

muscles

medially.

FNACwas

indicative

ofPA

Using

cervical

transparotid

approach,

superficialanddeep

lobe

parotidectom

yperformed

separatelyto

preserve

facialnerve

branches

Increasedin

size

over

2mon

ths

Pleom

orph

icadenom

a

Sergietal.

(2008)

[17]

38/F

Left

Noextraoral

swellin

g.Intraoral

masslateraltothe

softpalateand

displacing

itacross

themidlin

e

MRIshow

edinho

mogeneous,

expansivemass

arisingfrom

the

deep

lobe

ofthe

parotidglandand

measuring

5:5×5:5

cmin

thelateral

pharyngealspace.

The

masswas

seen

displacing

the

pterygoidand

pharyngealmuscles

medially.FNACwas

indicative

ofPA

Separatesuperficial

anddeep

lobe

parotidectom

ythrough

transcervical,

mandibu

larsplit

approach

topreserve

facialnerve

branches

Painwhile

swallowingand

sensationof

foreignbody

inthethroat

since

5mon

ths

Pleom

orph

icadenom

awithanu

cleusof

carcinom

aex-PA

Postoperative

radiotherapy

Takaham

aetal.

(2008)

[18]

78/M

>30years

Right

30cm

Large,multino

dular

preauricular

mass

extend

ingto

the

subm

andibu

lar

region

andcrossing

themidlin

e.Fo

cal

areasof

ulceration

inthelower

partof

themass

Onlyclinical

exam

ination

Totalparotidectom

y28

×20

×16

cm(4.0kg)

Pleom

orph

icadenom

a

Bhu

tta(2009)

[19]

63/F

Left

Slow

-growingmass

intheleftsuperficial

parotid

Onlyclinical

exam

ination

Excisiondo

nein

1993,followed

bymultiplerecurrences

managed

surgically

throughexcision

from

1995-2006

Earlylesion

was

suggestive

ofPA.

Recurrent

lesion

sresembled

PAwith

high

mitoticrate

andno

malignancy

45Gyexternal

beam

radiation

therapy(in25

fraction

s)given

in2000

toprevent

recurrence

In2006,C

Tshow

edaright

kidn

eymass,

diagno

sedas

metastasizing

PAby

histology

(typicalfeatures

ofPAwith

positive

Ki67

staining)


Table1:Con

tinu

ed.

Autho

r(year)

Patient

demograph

ics

Preop

erativeevaluation


Postoperative

period

Age

(in

years)/gender

Duration

oflesion

Affected

side

Clin

ical

dimension

Clin

ical

presentation

Investigations

Procedu

reResected

dimension

Reasonfor

surgery

Histologicalfi

ndings

Postoperative

course

Follow-up

Karpo

wiczetal.

(2010)

[20]

45/M

Right

Subcutaneous

parotidmasswith

ipsilateralcervical

lymph

adenop

athy

involvingmultiple

nodes.Associated

withseverepain

and

rapidincrease

insize.C

linically

staged

asstageIva

malignant

disease

Onlyclinical

exam

ination

Totalparotidectom

ywithcomprehensive

neck

dissection

Non

encapsulated

tumor

measuring

abou

t3.5cm

Severe

pain

and

rapidincrease

insize

Malignant

epithelial

cells

ina

chon

drom

yxoidstroma

indicative

ofcarcinom

aex-PA.M

alignant

foci

includ

edhigh-grade

squamou

scell

carcinom

aand

adenocarcino

ma.One

ofthecervicallymph

nodesshow

edevidence

ofmetastaticcarcinom

a.Im

mun

ohistochem

istry

identified

amelanom

acompo

nent

Twomon

ths

postsurgery,the

patientrepo

rted

severe

pelvic

pain,d

iagnosed

asmetastatic

bone

disease

throughMRI

Patient

died

3mon

ths

postsurgerydu

eto

metastatic

disease

Cetin

etal.

(2012)

[21]

55/F

20years

Left

15×15

×20

cm

Largepreauricular

massextend

ingto

cervicalregion

s,withoverlyingskin

atroph

icand

vascular

USG

show

eda

lobu

latedmassin

theparotidgland

withbo

thho

mogeneous

and

heterogeneou

secho

textures

Totalparotidectom

yPleom

orph

icadenom

a

Morariu

etal.

(2012)

[22]

42/M

Right

Largemassarising

from

thelateral

pharyngealwall,

displacing

thesoft

palateanduvula,

andnarrow

ingthe

pharyngealairw

ay.

Associated

symptom

sof

painfulswallowing,

heavysnoring,and

sleepapneaforpast

1year

MRIshow

eda

circum

scribedmass

lesion

7×6×

4cm

extend

ingfrom

the

deep

lobe

ofthe

parotidglandinto

theparaph

aryngeal

spacewithfluid

spaces

and

septation.

CT

angiogram

while

show

ingsplayed

internaland

externalcarotid

arteries,ruled

out

anyabno

rmal

vascularity.

TransoralFN

AC

was

indicative

ofPA

Deeplobe

parotidectom

ythrough

transparotid

approach

Pharyngod

ynia

andno

cturnal

hypo

xia

symptom

s

Pleom

orph

icadenom

a

Patient

repo

rted

relieffrom

nocturnal

hypo

xia,

snoring,and

sleepapnea

symptom

s,po

stop

eratively

6-mon

threcurrence-free

follow-up


Table1:Con

tinu

ed.

Autho

r(year)

Patient

demograph

ics

Preop

erativeevaluation


Postoperative

period

Age

(in

years)/gender

Duration

oflesion

Affected

side

Clin

ical

dimension

Clin

ical

presentation

Investigations

Procedu

reResected

dimension

Reasonfor

surgery

Histologicalfi

ndings

Postoperative

course

Follow-up

Yoshida

etal.

(2013)

[23]

40/F

17years

Left

Smallp

arotid

swellin

gbefore

17years,diagno

sedas

PAby

FNAC.

Surgerydelayedfor

10yearsdu

eto

patient’s

fear

and

then

lostto

follow-

up.Swellin

ggrew

rapidlyin

past6

mon

ths,causing

gaitdisturbanceand

skin

ulceration

with

foul-smellin

g,bloo

dydischarge

from

thelower

partof

lesion

CTshow

eda

nodu

larmass

arisingfrom

the

parotidglandand

attached

inits

deeper

aspectto

the

carotidsheath.

Evidenceof

metastasisin

chest

radiograph

owingto

bilateralh

ilar

lymph

adenop

athy

andcoin-shaped

radiolucency

inthe

rightlung.Incision

biop

sywas

indicative

ofPA,

withclinical

suspicionof

malignancy

Totalparotidectom

yanden

bloc

resectionof

the

tumor

alon

gwith

thelower

portionof

theauricle

25×28

×18

cm(4.80kg)

Rapid

grow

thof

tumor

inlast6

mon

thswith

cervicaland

thoracic

scoliosisand

gaitdisturbance

Nearly80%

ofthe

resected

tumor

sections

show

edevidence

ofPA.

Sections

ofthetumor

near

theulceratedareas

show

edun

differentiated

malignant

cells

indicative

ofcarcinom

aex-PA

Postoperative

adjuvant

chem

otherapy

formetastasis

6-mon

thfollow-upwith

nolocal

recurrence

Pam

uketal.

(2014)

[24]

82/F

20years

Right

13×13

×10

cm

Large,multilobu

lar

preauricular

mass

withareasof

ulceration

and

necrosison

overlyingskin

CTshow

edagiant,

exop

hyticmassin

thesuperficiallobe

oftheparotidgland

withmultiple

necroticspaces

and

enhanced

vascularity.

Incision

albiop

sywas

indicative

ofa

salivarygland

neop

lasm

witho

utrulin

gou

tmalignant

transformation

Superficial

parotidectom

ywith

excision

ofoverlying

ulceratedskin

14×12

×9c

m

Pleom

orph

icadenom

awithmultiplefociof

neop

lasticproliferation

,alon

gwithcellu

lar

atypiaandnecrosis.

Finald

iagnosis

carcinom

aex-PA

Postoperative

radiotherapy

60Gy

Patient

died

8mon

ths

postsurgery

dueto

cerebrovascular

accident

Datarkarand

Deshp

ande

(2014)

[25]

40/F

Right

Large,firm

intraoral

massarisingfrom

thelateral

pharyngealwall,

displacing

thesoft

palateandcrossing

midlin

e.Associated

symptom

sof

difficulty

insw

allowingand

breathing,andsleep

apneaforpast6

mon

ths

CTshow

edparaph

aryngeal

spacemass

extend

ingmedially

across

themidlin

eandlaterally

betweenthe

posteriorbo

rder

oframus

andstyloid

process.MRI

show

edlobu

lated,

homogeneous

mass

lesion

extend

ing

Deeplobe

parotidectom

ythrough

transcervical,

mandibu

larsplit

osteotom

yapproach

5:5×

6:5×3:5c

m

Diffi

culty

insw

allowingand

breathing,and

sleepapnea

Pleom

orph

icadenom

a

Patient

repo

rted

relief from

sleep

apnea

symptom

s,po

stop

eratively


Table1:Con

tinu

ed.

Autho

r(year)

Patient

demograph

ics

Preop

erativeevaluation


Postoperative

period

Age

(in

years)/gender

Duration

oflesion

Affected

side

Clin

ical

dimension

Clin

ical

presentation

Investigations

Procedu

reResected

dimension

Reasonfor

surgery

Histologicalfi

ndings

Postoperative

course

Follow-up

from

thedeep

lobe

oftheparotidgland

withhypo

intense

septae

and

measuring

5:4×6:5

×3:5c

m,and

indentingon

lateral

pharyngealwall.No

involvem

entof

skull

base

orintracranial

extensionwas

observed.T

ransoral

FNACwas

indicative

ofPA

Sajid

etal.

(2015)

[26]

47/M

>7years

Right

26×20

cm

Large,no

dular

preauricular

mass

extend

ingup

tosubm

andibu

lar

region

inferiorly

andanteriorlyup

to2cm

posteriorto

thenasolabialfold

MRIshow

eda

heterogeneou

s,lobu

latedmassin

thesuperficiallobe

oftheparotidgland,

extend

ingmedially

upto

sterno

mastoid

andcarotidsheath.

FNACwas

indicative

ofPA

Superficial

parotidectom

ywith

excision

ofredu

ndantskin

22×24

×12

cm(1.8kg)

Pleom

orph

icadenom

a

Tarsitano

etal.

(2015)

[27]

83/M

>30years

Left

35×28

cm

Giant,

multino

dular,

pedu

nculated

mass

inthepreauricular

region

,extending

upto

thecervical

region

MRIsho

wed

agiant,

heterogeneou

smass

arisingfrom

the

superficiallobe

oftheparotidgland,

withwell-

demarcated

boun

daries

and

preservation

ofsurrou

ndingtissue

planes.C

Trevealed

prim

arybloo

dsupp

lythou

ghfacial

artery

and

numerou

ssm

all

feeder

vessels.

Incision

albiop

syconfi

rmed

the

diagno

sisof

PA

Extracapsular

dissection

ofthe

tumor

mass

33×27

×16

cm(7.3kg)

The

mass

becametoobig

andahind

rance

forthepatientto

ambu

late

Pleom

orph

icadenom

a

5-year

recurrence-free

follow-up


Table1:Con

tinu

ed.

Autho

r(year)

Patient

demograph

ics

Preop

erativeevaluation


Postoperative

period

Age

(in

years)/gender

Duration

oflesion

Affected

side

Clin

ical

dimension

Clin

ical

presentation

Investigations

Procedu

reResected

dimension

Reasonfor

surgery

Histologicalfi

ndings

Postoperative

course

Follow-up

Akintub

ubo

etal.(2016)[4]

60/M

>10years

Left

25×23

×17

cm

Giant,lob

ulated,

andpedu

nculated

massin

the

preauricular

region

,extend

ingup

tocervicalregion

,with

firm

consistency

andmeasuring

almostthesize

ofthepatient’s

head

CTshow

edalarge

softtissue

mass

arisingfrom

the

superficiallobe

oftheparotidgland

andpresenting

with

severalamorph

ous

calcification

s,bu

twitho

utanybo

nyinvolvem

ent.FN

AC

was

indicative

ofPA

Superficial

parotidectom

y(5.5kg)

Patient

had

delayedsurgery

dueto

financial

constraints

Pleom

orph

icadenom

awith

multiplefociof

microcalcification

s

Reactionary

hemorrhagein

theim

mediate

postop

erative

period

,managed

through

exploratory

ligation.

Transient

neurological

deficitof

the

buccalbranch

offacialnerve

6-mon

threcurrence-free

follow-up

Calvo-

Henriqu

ezetal.

(2016)

[28]

72/F

14years

Right

20×15

cm

Giant

preauricular

mass,fixedto

underlying

tissues

andassociated

with

facialnervedeficit

(Hou

se-Brackman

Grade

III)

CTshow

edawell-

definedparotid

masswithmixed

solid

andcystic

areas.The

mass

extend

edsuperiorly

upto

tempo

ral

muscleand

cervicallyup

tothe

hyoidbo

ne.F

NAC

was

indicative

ofmixed

tumor

ofsalivaryglandorigin

Extracapsular

dissection

oftumor

massalon

gwitha

superficialskin

island

(1.6kg)

Facialnerve

deficit(H

ouse-

Brackman

Grade

III)

persisted

postop

eratively

Swain(2016)

[29]

92/M

>25years

Right

20×15

cm

Large,multino

dular

preauricular

mass

withskin

ulceration

dueto

repeated

traumaforpast6

mon

ths

CTshow

edawell-

definedmass

involvingthe

superficiallobe

oftheparotidgland.

FNACwas

indicative

ofPA

Superficial

parotidectom

ywith

preservation

offacialnerve

branches

Skin

ulceration

dueto

repeated

traumaforpast

6mon

ths

Pleom

orph

icadenom

a

Chaoetal.

(2017)

[30]

83/F

>20years

Right

Patient

presented

withaslow

-grow

ing,

preauricular

mass1

year

agowhich

was

provisionally

identified

asPA

throughFN

AC.

Patient

however

delayedsurgerydu

eto

person

alreason

s.Rapidly

proliferating

CTshow

eda

heterogeneou

sparotidmass

measuring

9×8:4

cmwithfociof

necrosisand

calcification

.The

masswas

inclose

proxim

ityto

inferior

aspectof

externalauditory

canaland

was

invading

Enbloc

resection

withtotal

parotidectom

y.Facialnerve

branches

except

the

buccalbranch

were

preserved.

The

buccalbranch

was

encasedin

tumor.

Selectiveneck

dissection

(levels

I-III)alon

gwith

resectionof

10.5cm

diam

eter

Rapid

grow

thwithskin

ulceration

inthe

last1year

Truemalignant

mixed

tumor

with

extensivefoci

ofnecrosisandpo

orly

differentiated

adenocarcino

ma

andchon

drosarcoma

compo

nents.No

histologicalevidence

oforiginalPAseen

Postoperative

radiotherapy

60Gy

At3-year

follow-up,

noloco

region

alrecurrence

was

observed.

Patient

however

presentedwith

lung

andliver

nodu

leson

PET

scan


Table1:Con

tinu

ed.

Autho

r(year)

Patient

demograph

ics

Preop

erativeevaluation


Postoperative

period

Age

(in

years)/gender

Duration

oflesion

Affected

side

Clin

ical

dimension

Clin

ical

presentation

Investigations

Procedu

reResected

dimension

Reasonfor

surgery

Histologicalfi

ndings

Postoperative

course

Follow-up

exop

hytic,firm

,multilobu

lated

grow

thwithskin

ulceration

and

bleeding

wereseen

inthesamelesion

inthelast1year.Facial

nervefunction

was

intact

sterno

mastoid

and

massetermuscles.

Superficiallyskin

erosionwas

seen.

Noevidence

oflymph

node

orbo

nyinvolvem

ent.FN

AC

was

suggestive

ofcarcinom

aex-PA

infratem

poraland

paraph

aryngeal

spaces.Soft-tissue

reconstruction

with

anterolateralthigh

free

flap

Alnofaieetal.

(2020)

[31]

25/F

10years

Right

25×25

×15

cm

Irregular,

multilobu

lated,

giantmasswitha

sessile

base

inthe

rightparotidregion

extend

ingto

the

neck.O

verlying

skin

appeared

erythematou

swith

prom

inent

vasculatureandno

discharge.Sw

ellin

gwas

fixedto

underlying

tissues

andfacialnerve

function

was

unaffected

CTshow

eda

heterogeneou

smass

lesion

arisingfrom

theparotid.

MRI

show

edalobu

lated

heterogeneou

smass

withmultilocular

cysticchangesand

measuring

12×10

×12

cm.N

oextensionto

retrom

andibu

laror

paraph

aryngeal

spaces.F

NACwas

suggestive

ofPA

Superficial

parotidectom

ywith

preservation

offacialnerve

branches

18×17

×11:5cm

(1.5kg)

Patient

was

mentally

challenged

and

patient’s

mother

requ

ested

surgeryas

the

masshad

becometoo

largeand

hind

ered

daily

activities

Pleom

orph

icadenom

a

1-year

recurrence-free

follow-up

Pareeketal.

(2020)

[32]

(caseseries

comprising15

giantparotid

PA)

30-81years

(mean—

50.3)/5

males

and10

females

5-20

years

Right—9;

left—6

Alllesion

swere

greaterthan

10cm

indiam

eter

(range

10-

25cm

)

Majorityof

the

lesion

spresentedas

irregularor

ovoid

parotidmasseswith

well-defined

margins

and

overlyingskin

was

ulceratedin

2cases.

Non

eof

thecases

hadpreoperative

facialnerve

weakn

ess

Acombination

ofUSG

,CT,M

RI,and

FNACto

arrive

ata

provisional

diagno

sisof

PA.

One

case

was

preoperatively

diagno

sedwith

malignant

change

basedon

FNAC

Total

parotidectom

y—10;

totalp

arotidectomy

+neck

dissection

—1;

superficial

parotidectom

y—3;

enucleation—1.

Facialnerve

preservedinallcases

(2.0-3.5kg;

mean—

2.7)

Majorityof

the

patientsdelayed

surgerydu

eto

poor

awarenessand

underprivileged

socioecono

mic

status

Allcaseswere

histologicallyconfi

rmed

asPA,excepton

ecase

which

show

eda

malignant

change

Transient

facial

nervedeficitin

2patientswhich

recovered

within6

mon

ths.

Postoperative

radiotherapy

onlyforthe

malignant

case

Minim

um6-mon

threcurrence-free

follow-up

M:m

ale/F:female;CT:com

putedtomograph

y;MRI:magneticresonanceim

aging;FN

AC:fine-needleaspiration

cytology;P

A:pleom

orph

icadenom

a;USG

:ultrason

ograph

y;PET:positronem

ission

tomograph

y.


16–18, 21, 32] (Table 1). Since the present case was that of aPA involving superficial parotid only (Figures 1 and 2), thepatient was surgically managed through ECD (Figure 3),avoiding any iatrogenic damage to the facial nerve(Figure 5). The surgical techniques for resecting PA haveevolved over the last century and have essentially focusedon preserving anatomic and functional integrity of the facialnerve and its branches [1, 7]. While intracapsular removalwas advocated, during the late 19th and early 20th centuriesin an attempt to avoid facial nerve injury, the techniquewas abandoned due to its high risk of recurrence (≥45%)[1, 7]. This leads to the popularity of SP, associated with avery low recurrence rate (≤2%), but still carrying a risk offacial nerve injury, Frey syndrome, and loss of facial contour[1]. In the last 2-3 decades, ECD has gained significance as asurgical technique which involves tumor resection along withthe capsule and a thin rim of extracapsular normal tissue,without attempting to identify or dissect the facial nerveand its branches [1]. Based on literature reviews, Kato et al.[1] and Bonavolontà et al. [7] reported that ECD is safe, iseconomical, and reduces operating time and risk of morbid-ity. They further considered it as the treatment of choice formobile, benign tumors involving the superficial lobe of theparotid gland [1, 7]. Moreover, traction due to gravity ingiant PA causes the tumor mass to descend away from thefacial nerve and its branches, thereby facilitating ease of dis-section, as encountered in the present case [10].

Several surgical approaches to remove PA and otherbenign parotid gland tumors involving the deep lobe andextending to the lateral pharyngeal and parapharyngealspaces have been reported [11]. These include cervical, cervi-cal-transpharyngeal, infratemporal fossa, parotid-cervical,transoral, and transparotid approaches. In the presentreview, 9 cases of PA were reportedly involving the deep lobeof parotid and extending into pharyngeal spaces. Thecervical-transparotid surgical approach was used for resec-tion in 6 cases [11, 13, 16, 17, 22], a transcervical, split-mandibulotomy approach was used in 2 cases [17, 25], andone case was managed through a transoral approach using“Double-Y” incision in soft palate [16] (Table 1). Postopera-tive complications following surgical resection of parotid PAare similar to that of other benign SGT [1, 4, 7, 23]. Theseinclude hemorrhage, hematoma, seroma, fistula, hypoesthe-sia, scarring, Frey syndrome, transient facial nerve injury,and facial paralysis [7]. While these complications are report-edly associated with all surgical techniques mentionedbefore, ECD was associated with a significantly lower riskof hypoesthesia, Frey syndrome, and facial nerve injury andparalysis [7]. Nevertheless, when dealing with large parotidtumors with suspected malignancy, which mandate identifi-cation and dissection of facial nerve branches, no significantdifferences were observed in the outcomes and complicationsbetween antegrade and retrograde dissection techniques [30].Postoperative complications reported in the current reviewinclude reactionary hemorrhage immediately after surgery[4] and transient facial nerve deficit which recovered in dura-tions ranging from one month to 6 months [4, 11, 14, 16, 17,32] (Table 1). Although there were no documented cases ofpermanent facial nerve injury, Calvo-Henriquez et al. [28]

reported a case of preoperative “House-Brackman GradeIII” facial nerve deficit, which persisted postoperatively.

In addition to the long-standing nature of the tumor andits large size, the currently reported case also presented withatypical histological findings. While the histological picturewas predominantly coherent with that ofPA characterizedby epithelial tissue dispersed in a chondroid and myxoidmatrix [34], there was marked squamous metaplasia and ker-atin cyst formation (Figure 4). These findings are unusual inPA of the parotid gland and lead to a high index of suspiciontowards a diagnosis of mucoepidermoid carcinoma or squa-mous cell carcinoma [35]. However, similar findings havebeen reported in the literature in PA arising in labial and pal-atal minor salivary glands, wherein malignant transforma-tion is highly suspected and ranges from 2 to 23% [6, 35].Squamous metaplasia of glandular cells is attributed to hyp-oxia within the growing tumor and combined with keratincysts; they mimic cutaneous appendages and are termed as“cystic pleomorphic adenoma with extensive adnexa-like dif-ferentiation” [35]. It has further been emphasized that theabove findings during the histological examination of sus-pected pleomorphic adenomas warrant meticulous histo-pathological evaluation to avoid surgical overtreatment [6,35]. Analyzing the histological findings in the present review,only one case was associated with cartilaginous metaplasia[10], without any evidence of malignant change, similar tothat observed in our case too. Nevertheless, malignant trans-formation was reported based on final histopathologicalexamination in 10 cases, including 5 cases of carcinomaexpleomorphic adenoma (CA-ExPA) [17, 20, 23, 24, 32],one case of adenocarcinoma along with PA [15], 3 cases ofmixed malignant tumor arising in PA [8, 12, 30], and onecase of metastasizing PA with renal metastasis [19](Table 1). Interestingly, one of the cases of CA-ExPA alsohad a malignant melanoma component, arising possiblyfrom melanocytes within parotid tissue [20].

Malignant transformation of PA is reported at around12% and comprises nearly 4% of all SGT [20]. According tothe World Health Organization (WHO) classification ofSGT, malignant tumors arising in PA were originally classi-fied either into CA-ExPA or the relatively rare mixed malig-nant tumor with epithelial and mesenchymal components [8,12]. While metastasizing PA, with metastatic lesions exhibit-ing histological characteristics of PA and no malignantchange was originally considered a malignant variant, it hasbeen relegated to the benign category as per the WHO classi-fication (2017) of SGT [36]. Although rare, metastasizing PAis frequently associated with multiple recurrences of the pri-mary tumor. Bhutta et al. [19] reported a case of metastaticrenal PA, with multiple postsurgical recurrences of theparotid PA in over a decade. Based on a retrospective studyof 221 patients with PA and 15 patients with CA-ExPA, Seoket al. [37] reported increasing age, regional lymph nodeinvolvement (>5mm), and MRI apparent diffusion coeffi-cient as the distinguishing clinical and radiographic featuresof CA-ExPA. In terms of histology, cellular atypia and stro-mal hyalinization have been regarded as the key delineatingfeatures of CA-ExPA from benign PA [36, 38]. Based onimmunohistochemistry (IHC), loss of expression of PLAG-


1 (pleomorphic adenoma gene-1) protein and overexpres-sion of Ki-67, p53, and HER-2 (human epidermal growthfactor receptor-2) are considered suggestive of malignanttransformation in otherwise benign PA [38, 39]. At a molec-ular genetic level, malignant transformation of PA is furthercharacterized by PLAG-1/HMGA-2 (High Mobility GroupAT-Hook 2) fusion and rearrangement, p53 mutation, andHER-2 amplification [36, 38, 39].

In the present review, PA with malignant transformationwas treated surgically, followed by radiotherapy for locore-gional disease and chemotherapy for distant metastases.Within postoperative follow-up periods ranging from 6months to 5 years, only one case of recurrent benign PAwas reported in the review [19]. Among tumors with malig-nant change, locoregional recurrence was reported in onecase of mixed malignant tumor [8], cervical lymph nodemetastasis was seen in 2 cases [12, 20], and distant metastasisto the anterior chest wall, lungs, liver, pelvis, and kidney wasobserved in 5 cases [12, 15, 19, 20, 30]. While there was nomortality associated with benign PA or its surgical treatment,3 patients with malignant transformation died within 6months after surgery as a result of metastatic disease [8, 15,20]. The longest recurrence-free follow-up for a giant parotidPA in the present review was 5 years [27], and this was stilllesser than the 7-year recurrence-free follow-up observed inour case.

4. Conclusion

Giant parotid PA is rare, and to the best of our knowledgefrom indexed literature, this is one of the very few casesreported in this geographical region (Saudi Arabia). Apartfrom its rarity, the present case is being reported for itslong-standing clinical presentation, successful surgical man-agement through ECD without any postoperative complica-tions or facial nerve deficit, atypical histologicalpresentation, and long-term recurrence-free follow-up. Inaddition to complete tumor removal, ECD helped preservethe integrity of facial nerve branches. Interestingly, the pres-ent case of giant parotid PA was benign in spite of associatedsquamous metaplasia and keratin cyst formation identifiedhistologically in the resected specimen. Nevertheless, thismandated a long-term follow-up of the patient. Therefore,based on this case report, clinicians must be aware of atypicalhistological presentation associated with parotid PA and plansuitable surgical management and follow-up, to achieve com-plete tumor removal and avoid morbidity. Lastly, attemptsmust be made to diagnose and manage PA at an early stageand before they reach gigantic proportions, through betterpublic health care initiatives and creating awareness amongall physicians and patients.

Ethical Approval

This case report was ethically approved by the ethical com-mittee at the College of Dentistry Research Center, King SaudUniversity, Riyadh, Saudi Arabia.

Consent

Informed consent was obtained from the patient.

Conflicts of Interest

The authors report no conflicts of interest with respect to thepublication of this article.

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