Ascending Colon Intussusception due to a Adenocarcinoma (2 of 6)

The appearance of this tumor is that of a enormous polyp that degenerated in a neoplasia.

Adult intussusceptions are rare entities that are almost
always associated with a demonstrable lead point.

General Gross Description

• The gross appearance is dependent on the stage of the
tumor.
• Early invasive carcinoma may maintain the appearance of
the original adenoma either polypoid or sessile.
• More commonly, the tumor has obliterated evidence of the
underlying adenoma and when first seen is a firm, white,
flat, well demarcated mucosal lesion with raised rolled
margins, often with central ulceration.
• Over time, the lesion spreads circumferentially through
circular lymphatics to produce a constricting napkin-ring
lesion in the mucosa.
• As mucosal spread occurs, tumor also invades the full
thickness of the muscular wall, and only at this stage is
tumor seen grossly involving the perirectal fat, or
mesentery.
• Cecal lesions often have a different appearance because
of the large volume of space in which they can grow before
producing symptoms. Cecal carcinomas often cover large
areas of the cecum with fungating sessile or bulky lesions
which can be extensively necrotic.
• Because of their long growth time before discovery cecal
lesions often are seen as large deeply invasive tumors with
attachment to the adjacent peritoneal wall.