Case study head and neckGerrit Engelbrecht

Department radiology

UFS

Case

24 year old male

Refered from ophtalmology Fluctuating mass, painless, left temporal region.( aware of it for

several months, insidious in onset )

Mild proptosis of the left eye.

No visual field fallout.

No cranial nerve fallout.

Normal movement of the globe.

Neurological exam normal.

No systemic illnesses.

No histology available

MRI and CT

T2* FGRE

T2 Ax

T2 Flair

Sag T1

AxT1-fs SE S 3mm

Cor T1-fs SE S 4 mm

AxT2 FSE H 3 mm

Ax T1 SE + C

Cor T1 +C FS SE 4 mm

Ax T1+ C FS SE S 3 mm

Scout of CT

CT pre and post contrast

General features

Best diagnostic clue:

Cystic, well-demarcated, anterior extraconal mass with fatty, fluid or mixed contents

Location

Tethered to orbital periosteum, near suture lines

Majority extraconal in superolateral aspect of anterior orbit, at frontozygomatic suture (65-75%)

Remainder mostly in superonasal aspect, at frontolacrimal suture, but can occur anywhere

Size

Typically less than 1-2 cm in superficial lesions

Larger in deep, complicated lesions

Morphology

Ovoid, well-demarcated cystic mass

Most show thin definable wall (75%)

No nodular soft tissue outside cyst (80%)

Contents

Internal fat or fluid features; may be mixed or contain debris

Lipid components evident in 40-50% of lesions

Fluid-fluid levels in 5 % of lesions

Dermoid cysts typically but not exclusively contain fat and appear more heterogeneous

Epidermoid cysts typically have features similar to fluid and appear more homogeneous

Subtypes

Superficial (simple, exophytic)

Typically smaller, discrete, rounded

Present in early childhood

Deep (complicated, enclophytic)

More insidious, frequent bony changes

May extend into sinuses, high deep masticator space, or intracranially

Radiographic findings

Scalloped bony lucency with sclerotic margins

CT Findings NECT

Hypodense fat in about half Density -30 to -80 HU

Calcification in 15% Fine or punctate, in cyst wall

osseous remodeling in majority of lesions (85%)

Pressure excavation; smooth, scalloped margins

Thinning of bone, may cause focal dehiscence

Bony tunnel, cleft, or pit in up to one-third, leading to “dumbbell appearance

Irregular margins indicate rupture and inflammatory reaction

Bony changes less common in superficial lesions

CECT Mild, thin, rim-enhancement Irregular inflammatory

enhancement if ruptured

MR Findings

T1WI Strongly hyperintense (cf

vitreous) if fatty contents

Isointense or slightly hyperintense otherwise

T2WI Isointense or mildly

hypointense (cf vitreous)

Heterogeneous debris

TI C+ Thin rim-enhancement

More extensive inflammation if ruptured

Diffusion and FLAIR Epidermoid cysts show

high signal as in other areas of CNS imaging

Ultrasonographic findings

Adequate for evaluation of simple superficial lesions without posterior extension

High internal reflectivity, variable attenuation

Debris may impair determination of cystic nature

Pathology (general features)

Developmental mass, non-neoplastic contents

Epidermoid: Desquamated keratinaceous debris, cholesterol; thin capsule

Dermoid: Keratin, sebaceous secretions, lipid metabolites, hair; fibrous capsule

Etiology

Congenital inclusion of dermal elements at site of embryonic suture closure

Sequestration of trapped surface ectoderm

Epidemiology

Present from birth; spontaneous occurrence

10% of head and neck dermoid and epidermoid cysts are periorbital

5% of orbital masses

Gross pathological features

Whitish, well-delineated mass

Connected to orbital periosteum by fibrovascular tissue

Oily or cheesy material that is tan, yellow, or white

May contain blood or chronic blood products

Microscopic features Dermoid

Contains dermal structures, including sebaceous glands and hair follicles, blood vessels, fat and collagen within a fibrous capsule

Sweat glands in minority (20%)

Lined by keratinizing squamous epithelium

Epidermoid Inner surface of thin capsule lined by

keratinizing, stratified epithelium

Half show disruption of lining indicating rupture at some point

Inflammatory changes in 40%

Granulomatous reaction, particularly in deep, complicated lesions

Presentation

Demographics

Age

Most frequently presents in childhood and teenage

Mean age in late teens to twenties

Simple, superficial lesions often present in infancy

May present or grow at any age

Occasionally will appear in adult and grow significantly over several months

Gender: Equal or slight male predominance

Natural history and prognosis

Benign lesion, usually cosmetic considerations

Very slow growth, usually dormant for years

Present during childhood but small and dormant

Becomes symptomatic during rapid growth phase ¡n young adult

Sudden growth or change following rupture

Significant inflammation and increased size

Rarely fistula may occur

Treatment

Surgical resection is curative

Entire cyst must be removed to prevent recurrence, including growth center at periosteal interface

Approach depends on location in orbit

Lesions evident in early childhood should be removed to avoid traumatic rupture

Steroids or non-steroidal drugs to calm inflammation in ruptured lesions

References

Grainger&Allison’s Diagnostic Radiology, Fifth Edition.

Head and neck Imaging, Fourth Edition, Peter M.Som & Hugh D Curtin.

Diagnostic imaging, Head and Neck, H. Ric Harnsberger

Differential diagnosis