Page 604 - Textbook of Pathology, 6th Edition

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SECTION III

Figure 20.47 Gross appearance of colorectal carcinoma. A, Right-sided growth—fungating polypoid carcinoma showing cauliflower-like growth
projecting into the lumen. B, Left-sided growth—napkin-ring configuration with spread of growth into the bowel wall.
Systemic Pathology

Right-sided colonic growths tend to be large, cauli- Microscopically, the appearance of right and left-sided
flower-like, soft and friable masses projecting into the growths is similar. About 95% of colorectal carcinomas
lumen (fungating polypoid carcinoma). are adenocarcinomas of varying grades of differentiation,
Left-sided colonic growths, on the other hand, have out of which approximately 10% are mucin-secreting
napkin-ring configuration i.e. they encircle the bowel wall colloid carcinomas (Fig. 20.48). The remaining 5% tumours
circumferentially with increased fibrous tissue forming include uncommon microscopic patterns like undifferen-
annular ring, and have central ulceration on the surface tiated carcinoma, signet-ring cell carcinoma, and adeno-
with slightly elevated margins (carcinomatous ulcers). squamous carcinomas seen in more distal colon near the
These differences in right and left colonic growths are anus. The histologic grades indicating the degree of
probably due to the liquid nature of the contents in the differentiation are: well-differentiated, moderately-
ascending colon leaving space for luminal growth on right differentiated and poorly-differentiated.
side, while the contents in left colon are more solid SPREAD. Carcinoma of the large intestine may spread by
permitting the spread of growth into the bowel wall. the following routes:
However, early lesion in left as well as right colon are
small, button-like areas of elevation. 1. Direct spread. The tumour spreads most commonly by
direct extension in both ways— circumferentially into the