Villous Adenoma

Published on 13/07/2015 by admin

Filed under Radiology

Last modified 13/07/2015

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 2666 times

 Accounts for 5-15% of colonic adenomas

IMAGING

• Polypoid lesion with nodular or frond-like surface on BE or CT colonography
• Location: Rectosigmoid > cecum > ascending colon > stomach > duodenum
• Villous adenoma is 1 histological type of adenomatous polyps (true neoplasms)
• Risk of cancer is related to tumor size, location, and proportion of villous change in adenoma
• Greater risk of carcinoma in villous tumors of stomach and duodenum than colon

image Stomach: Carcinoma in 50% of lesions 2-4 cm and in 80% of lesions > 4 cm in size
image Colon: Invasive carcinoma in up to 45% of cases
• CT: Large villous adenoma

image Low-attenuation, minimally enhancing, irregular polypoid mass
image Corrugated, feathery appearance due to trapping of enteric contrast
• Transrectal US; plus CT or MR for staging

TOP DIFFERENTIAL DIAGNOSES

• Colon carcinoma
• Fecal mass

PATHOLOGY

• Malignant potential: Lesions < 1 cm (5%), 1-2 cm (10%), > 2 cm (53%)

CLINICAL ISSUES

• Asymptomatic, diarrhea, pain, rectal bleeding, or melena
• Lesion closer to rectum: More likely to have diarrhea, electrolyte loss (hypokalemia and hyponatremia)
image
(Left) Graphic shows a polypoid mass image in the rectosigmoid colon having a shaggy, nodular surface, sometimes likened to the surface of a cauliflower.

image
(Right) Single contrast barium enema shows a large rectal mass image with a frond-like surface. Note the absence of a colonic obstruction, a typical feature of this soft and compressible tumor.
image
(Left) This 70-year-old man complained of frequent passage of watery stool, but had no symptoms of bowel obstruction. CT shows a large mass image that fills the rectum. Note large vessels image within and draining the mass.

image
(Right) Coronal CT reformation in the same case shows the huge size of the mass image, but no definite signs of invasion through the rectal wall and no metastases. The resected villous adenoma had foci of frank carcinoma.

TERMINOLOGY

Synonyms

• Villous tumor

Definitions

• Adenomatous polyp that contains predominantly villous (“shaggy” surface) elements

IMAGING

General Features

• Best diagnostic clue

image Polypoid lesion with nodular or frond-like surface on barium enema or CT colonography
• Location

image Rectosigmoid > cecum > ascending colon > stomach > duodenum
• Size

image Range from < 1 to > 10 cm in diameter
image Giant villous tumor: 10-15 cm
• Morphology

image Cauliflower-like sessile growth with broad base or flat “carpet” lesion
• Other general features

image Villous adenoma is 1 histological type of adenomatous polyps (true neoplasms)

– Tubular adenoma: > 80% of neoplastic polyps
– Villous adenoma: 5-15% of colonic polyps, villous morphology in > 75% of lesion
– Tubulovillous adenoma: 5-15% of all colonic polyps
image As adenoma increases in size, degree of villous change usually increases
image Risk of cancer is related to size, location, and proportion of villous change in adenoma
image Greater risk of carcinoma in villous tumors of stomach and duodenum than colon

– Stomach: Carcinoma in 50% of lesions 2-4 cm and in 80% of lesions > 4 cm
– Duodenum: Carcinoma in 30-60% of villous tumors > 4 cm
– Colon: Carcinoma in situ in 10% and invasive carcinoma in up to 45% of cases

Radiographic Findings

• Fluoroscopic-guided double contrast barium enema

image 2 types of villous adenomas

– Polypoid mass
– “Carpet” lesion
image Polypoid mass

– May look cauliflower-like within colon
– Nodular, “lace,” or “soap bubble” pattern
– Due to trapping of barium between frond-like projections (interstices)
– Malignant transformation in bulky adenoma: Annular lesion with shelf-like, overhanging borders
image “Carpet” lesion

– Flat, lobulated lesion
– Localized or extensive
image Localized “carpet” lesion: Subtle alteration in surface texture
image Extensive “carpet” lesion: Involves large area of colon, encircling lumen

– En face: Fine nodular, reticular pattern with sharply demarcated border
– Profile: Irregular contour in contrast to smooth, fine contour of adjacent normal bowel
image Malignant transformation in “carpet” lesion (↑ risk)

– Radiolucent nodules surrounded by barium-filled grooves (produce fine nodular or reticular pattern)
– Polypoid carcinoma with surrounding mucosal change represents underlying adenoma
– Seen in rectum, cecum, ascending colon, stomach, and duodenum
Buy Membership for Radiology Category to continue reading. Learn more here