Special polyp types Professor Neil A Shepherd Gloucester, UK NHSBCSP Pathology Day, London, November...

Special polyp types

Professor Neil A ShepherdGloucester, UK

NHSBCSP Pathology Day,London, November 21, 2007

Pathology and the NHSBCSP

• a polyp is any lesion raised above the level of an epithelial surface

• suddenly, with BCSP, there are lots more colonoscopies

• all done by experts with dye-spray of small lesions and EMR

• we might expect to see the occasional funny and we need to be alert

A classification of polyps of the colorectum

• adenomas• hyperplastic polyps• mixed polyps• inflammatory polyps• juvenile polyps• Peutz-Jeghers polyps • stromal polyps

• syndromic polyps – the triumvirate of polyposes, Cowden’s, Cronkhite-Canada, etc

Morson & Dawson, 2003



• syndromic polyps – polyposes, Cowden’s, Cronkhite-Canada, etc

• but some ‘polyps’ likely to be excised in BCSP are not in the list…..

68M. Polypoid nodule in rectum.

chromogranin

synaptophysin

normal 30 19.87%

cancer 24 15.89%

low risk polyps 20 13.25%

intermediate risk polyps

38 25.17%

high risk polyps 22 14.57%

abnormal result, not polyps

6 3.97%

refer for surgery (polyp)

5 3.31%

miscellaneous 6 3.97%

TOTAL 151 100%

Gloucestershire BCSP, January-October 2007

Hyperplastic polyps

• about 25% of all polyps

Issues:

• differentiating them from mixed polyps & serrated adenoma

• when they are large and right-sided and show SSP features

• when they show epithelial misplacement – inverted hyperplastic polyps

Inverted hyperplastic polyps

• closely related to right sided SSPs

Shepherd, 1991

Inflammatory polyps

• the most common ‘other’ entity in BCSP

• most are single/scanty and not related to CIBD (UC, CD, chronic infection such as schisto)

• in the age group of the BSCP population, diverticulosis-associated polyps, polypoid mucosal prolapse, post-interventional polyps more common

67F. BCSP. Diverticulosis and sigmoid colonic polyp.

Polypoid mucosal prolapse

• in the BCSP age group, lower rectal/anal most common: inflammatory cloacogenic polyp

• epithelial (villous) hyperplasia traps the unwary into calling them large villous adenomas

• may be seen in association with diverticulosis, at stomas, in SUMPS, etc

Polypoid mucosal prolapse at the anorectal junction

• a word of warning with inflammatory cloacogenic polyp

• 4 cases of adenomas of the lower rectum causing secondary polypoid mucosal prolapse

Parfitt & Shepherd, 2008

a

dc

b

Ki-67 p53

a b

c dKi-67 p53

Juvenile polyps• commonest polyp in childhood

• sporadic juvenile polyps do occur in adulthood but very rare in BCSP age group

• inflammatory polyps can look similar

• pretty unlikely to see juvenile polyposis….

Juvenile polyposis

‘Atypical juvenile polyps’ with dysplasia

Juvenile polyposis

• 1 in 80,000

• genetics becoming clearer but polymorphic: SMAD4 implicated in 25%

• high rates of colorectal cancer: life time risk - ? up to 30%

• dysplasia in atypical juvenile polyps

• ? surveillance ? prophylactic colectomy

Jass et al 1988,Woodford-Richens et al, 2000

Quick quiz question

SMAD 4 mutation is implicated in about a quarter of cases of this condition. What does SMAD stand for? Is it:

1. somatic mutation in Arctic drosophila

2. serine-methionine-arginine deletion

3. small mothers against decapentaplegia

Peutz-Jeghers polyposis

Peutz-Jeghers polyps

• syndrome about 1 in 100,000

• sporadic PJ-like polyps described but very rare

• ? relationship to ‘inflammatory myoglandular polyp’

• aren’t sporadic PJPs most likely to be post-inflammatory or post-mucosal prolapse?

Do sporadic Peutz-Jeghers polyps exist?

• 119 polyps in 38 patients

• most patients with PJ-like polyps were actually shown to have PJS (scanty colonic polyps in the syndrome)

• 8 left: three small bowel ones with PJ features; 5 colonic with suggestive features of PJPs (top GI pathologists could not tell for certain: mucosal prolapse could not be excluded). 40% in BCSP screening age group

• if they exist, sporadic colorectal PJ polyps are very rare

Burkhart et al. Do sporadic Peutz-Jeghers polyps exist? Experience from a large teaching hospital. AJSP, August

2007

Stromal polyps

• GIST• leiomyoma of muscularis mucosae• gastrointestinal schwannoma• neurofibroma• ganglioneuroma• epithelioid mucosal nerve sheath tumour• intestinal perineurioma• fibroblastic polyp• inflammatory fibroid polyp• that’s enough stromal polyps (Ed)

Small polypoid rectal nodules

Gastrointestinal schwannoma• 33 cases: 4 oesophagus, 24 stomach, 2 colon and 3 rectum

• mainly within muscularis propria and/or subserosa

• none encapsulated but all well circumscribed

• 32/33 cuff of lymphocytes

• only 12 originally called schwannoma

• S100 and vimentin +ve

• CD117, CD34, ASMA, desmin –ve

• nestin 80% positive; GFAP 64% positive

• all showed some nuclear pleomorphism: ? longevity: no mitoses

• all benign

Hou et al, 2006 (Histopathology)

Colonic polypoid mucosal lesions with mucosal entrapment and epithelial serration

A feature only rarely seen in GISTs

Colorectal intramucosal tumours with epithelial ‘entrapment’

Name First recognise

d

S100 CD 34 EMA Epithelial serration

Clinical features

neuro-fibroma

The year dot

+ ve -ve - ve occasionally

Most solitary

but @ NF

ganglio-neuroma

probably down to Carney…

+ve -ve -ve notdescribed

sporadicor NF-1, MEN 2b

benign fibroblastic

polyp of colon

2004 - ve +ve - ve 3/13 none

intestinalperi-

neurioma

2005 - ve -ve + ve 5/9 none

epithelioid NS tumour

2005 +ve +/-ve -ve 0/6 none

Benign fibroblastic polyp of colon:Eslami-Varzaneh F, Washington K, Robert ME, Kashgarian M,

Goldblum JR, Jain D. AJSP 2004; 28: 374-378.

CD34 positive: ‘neural’ markers negative

Intestinal perineurioma:Hornick JL, Fletcher CDM. AJSP 2005; 29: 859-865.

EMA positive: CD 117, CD 34, S100 negative

Mucosal epithelioid nerve sheath tumour: Lewin MR, Dilworth HP, Alfa AK, Epstein JI, Montgomery E.

AJSP 2005; 29: 1310-1315.

S100 & CD 34 positive: EMA & CD 117 negative

S 100 CD 34

Colorectal intramucosal tumours with epithelial ‘entrapment’ and surface

serration• extraordinary ‘new’ descriptions of three entities – smallish spindle

cell polypoid tumours with epithelial entrapment and surface epithelial serration

• ? recent recognition due to legislation to allow Medicare customers to undergo screening colonoscopy (2001)

• lesions are mainly of schwann cell/perineural cell origin

• differentiation by immunohistochemistry although specificity of these entities is a little doubtful..

Zamecnik & Chlumska, 2006 Groisman et al, 2006

• all are benign and should not be confused with more sinister lesions such as GISTs and others

Take home messages: special polyp types

• inflammatory polyp/polypoid mucosal prolapse most common after adenomas and HPs

• remember other lesions can be polypoid – leiomyoma of mm and rectal carcinoid – clinical, endoscopic and imaging correlation important

• the ‘hamartomatous’ polyps and syndromes are very rare (but not unheard of) in the BCSP age group

• serrated change can be a secondary phenomenon (polypoid mucosal prolapse, fibroblastic polyps, etc)

Special polyp types Professor Neil A Shepherd Gloucester, UK NHSBCSP Pathology Day, London, November...

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