tumors of colon pathology

1. TUMORS OF COLON

2. • COLORECTAL POLYPS:
o any growth or mass protruding from mucus
membrane into lumen.
o Large intestine > small intestine
o Recto - Sigmoid colon > proximal colon
o Classification :
1. Non – neoplastic
2. Neoplastic

3. Non – neoplastic polyps:
Types:
1. hyperplastic / metplastic polyps
2. Hamartomatous polyps
3. Inflammatory polyps
4. Lymphoid polyps

4. HYPERPLASTIC POLYPS:
• Most common
• Rectosigmoid
• Any age. Common: 60 – 70 yrs
• Areas of hyperplasia and areas of metaplasia
present
• Polyp + adenoma = malignant; polyp = benign
G / A:
• Multiple
• Sessile
• Smooth surface
• Small : < 0.5 cm
M / E:
• Long and cystically dilated glands lined by normal
epithelium

6. HAMARTOMATOUS POLYPS :
• Tumor like lesions containing abnormal mixture of
cells indegenous to that part.
• 2 types:
1. Peutz – Jeghers Polyps and Polyposis:
• Autosomal dominant defect
• Character: hamartomatous intestinal polyposis
with melanotic pigmentation on lips, mouth and
genitalia
G / A:
• Variable size. Common : large
• Multiple
• Pedunculated
M / E:

8. 2. Juvenile / retention polyps:
• Hamartomatous polyps occuring in children below
5 years
• Solitary
• Common in rectum
G / A:
• Spherical
• smooth surfaced
• Pedunculated
• 2 cm = dm
M / E:
• Cystically dilated glands containing mucus
• Normal mucus secreting epithelial cell lining
• If chronic ulceration of surface is present then
stroma shows inflammatory cell infiltrates.

10. INFLAMMATORY POLYPS:
• Re-epithelization of undermined ulcers and
overhanging margins in inflammatory bowel
diseases like ulcerative colitis and Crohn’s
disease.
G / A:
1. Multiple
2. Cylindrical to rounded
3. Minute nodules – several centimeters
M / E:
• Centre of the polyp contains connective tissue
core that contains some inflammatory cell
infiltrates and are covered by thin layer of
regenerating epithelial cells and cystically

12. Lymphoid polyps:
• Reactive hyperplasia of lymphoid tissues.
• Prominent in rectum and terminal ileum
• Also called rectal tonsils
G / A:
• Solitary / multiple
• Tiny
• Elevated lesions
M / E:
• Prominent lymphoid follicles with germinal
centres located in mucosa and submucosa
• Inflammed epithelial covering

14.  Neoplastic polyps:
• Colorectal adenomas which have potential for
malignant change
• 3 main varieties
1. Tubular
2. Villous
3. Tubulovillous

15. TUBULAR ADENOMA / ADENOMATOUS
POLYP:
• most common
• > 30 years
• Male > female
• Common in distal colon and rectum
• Asymptomatic / rectal bleeding
G / A:
• single or multiple
• sessile or pedunculated
• less than 1 cm or more
• large, spherical masses with an irregular

17. M / E:
• Branching tubules embedded in the lamina
propria.
• The lining epithelial cells are of large intestinal
type with diminished mucus secreting capacity,
large nuclei and increased mitotic activity.
• Variable degree of cytologic atypia ranging from
‘carcinoma in situ’ to frank adenocarcinoma

18. VILLOUS ADENOMA / VILLOUS PAPILLOMA:
• Less common.
• >60 years
• Both men and women.
• Often in the distal colon and rectum.
• invariably symptomatic
• rectal bleeding, diarrhoea and mucus being the
common features.
• The presence of severe atypia, carcinoma in
situ and invasive carcinoma are seen more
frequently.

19. G / A:
• round to oval exophytic masses
• sessile
• 1 to 10 cm or more in diameter.
• surface may be haemorrhagic or ulcerated.
M / E:
• many slender, finger-like villi, which appear to
arise directly from the area of muscularis
mucosae.
• Each of the papillae has fibrovascular stromal
core that is covered by epithelial cells varying
from apparently benign to anaplastic cells.

21. TUBULOVILLOUS ADENOMA / PAPILLARY
ADENOMA / VILLOGLANDULAR ADENOMA:
• intermediate form of pattern between tubular
adenoma and villous adenoma
• most common
• > 30 years
• Male > female
• Common in distal colon and rectum
• Asymptomatic / rectal bleeding

22. G / A:
• single or multiple
• sessile or pedunculated
• less than 1 cm or more
• large, spherical masses with an irregular surface.
M / E:
• Branching tubules embedded in the lamina
propria.
• The lining epithelial cells are of large intestinal type
with diminished mucus secreting capacity, large
nuclei and increased mitotic activity.
• Variable degree of cytologic atypia ranging from
‘carcinoma in situ’ to frank adenocarcinoma

24.  OTHER BENIGN TUMORS ARE:
1. Leiomyomas
2. Leiomyoblastoma
3. Neurilemmoma
4. lipoma
5. vascular tumours - haemangioma,
lymphangioma

25. MALIGNANT TUMORS :
1. Colorectal Carcinoma
2. leiomyosarcoma
3. malignant lymphoma
4. Hindgut carcinoids may occur in the rectum
and colon

26. COLORECTAL CARCINOMA:
• commonest form of visceral cancer
• Age : 60 years and above
• Common in males than females
ETIOLOGY:
1. Geographic variations
2. Dietary factors.
3. Adenoma-carcinoma sequence.
4. Hereditary non-polyposis colonic cancer
(HNPCC or Lynch syndrome)
5. Other factors

28. GROSS ANATOMY:
• Right-sided colonic growths:
• large
• cauliflower-like, soft and friable masses
projecting into the lumen (fungating polypoid
carcinoma).
• Left-sided colonic growths:
• napkin-ring configuration - they encircle the
bowel wall circumferentially with increased
fibrous tissue forming annular ring
• central ulceration on the surface with slightly
elevated margins (carcinomatous ulcers).
• However, early lesion in left as well as right
colon are small, button-like areas of elevation.

30. Microscopically:
• the appearance of right and left-sided growths is
similar.
• adenocarcinomas of varying grades of
differentiation, most are mucin-secreting colloid
carcinomas while some are uncommon microscopic
patterns like undifferentiated carcinoma, signet-ring
cell carcinoma, and adenosquamous carcinomas
seen in more distal colon near the anus.
• The histologic grades indicating the degree of
differentiation are: well-differentiated, moderately
differentiated and poorly-differentiated

32. SPREAD:
1. Direct spread
2. Lymphatic spread
3. Haematogenous spread
CLINICAL FEATURES:
1. Melaena
2. Change in bowel habits, more often in left-
sided growth
3. Cachexia
4. Anorexia
5. Anaemia, weakness, malaise.