Page 432 - Concise Pathology for Exam Preparation ( PDFDrive )

14 The Oral Cavity and Gastrointestinal Tract 417

Q. Enumerate the various modalities for diagnosing colorectal
carcinoma.
Ans. Modalities for diagnosing colorectal carcinoma:
1. Digital rectal examination
2. Testing for occult blood loss
3. Double contrast barium enema (apple core appearance), sigmoidoscopy or colonos-
copy and endoscopy directed biopsy
4. Computed tomography and other radiographic techniques to look for the primary as
well as the spread
5. Serum markers like CEA (has little diagnostic value as levels become significantly elevated
only after the tumour has achieved a considerable size; CEA levels also elevated in carci-
noma of lung, breast, ovary, urinary bladder and prostate and nonneoplastic disorders
like alcoholic cirrhosis, pancreatitis and ulcerative colitis)
6. Molecular detection of APC mutations in epithelial cells from stool is being considered
as a diagnostic tool

Q. Differentiate between right-sided and left-sided colonic
carcinoma.
Ans. Differences between right-sided and left-sided colonic carcinoma are listed in Table 14.9.

TABLE 14.9. Differences between right-sided and left-sided colonic carcinoma

Features Right-sided colonic carcinoma Left-sided colonic carcinoma
Site Caecum and ascending colon Descending colon and sigmoid
Gross appearance Fungating polypoid carcinoma. Large cauli- Ulcerative or ulceroinfiltrative lesions pro-
flower-like soft friable mass projecting into ducing a napkin ring constriction (annu-
lumen lar ring). May show central ulceration
with slightly elevated margins
Clinical features Bleed readily; fatigue, weakness, iron defi- Occult bleeding, change in bowel habits,
ciency anaemia. Obstructive symptoms crampy lower left quadrant discomfort,
less common due to a larger area available constipation and obstructive symptoms
for the tumour to expand more prominent
Diagnosis Late Early (due to early onset of obstructive
symptoms)

Q. Describe the clinicopathological features of carcinoid tumour
of GIT.
Ans. Salient Features of Carcinoid Tumour of GIT
• Derived from cells of neuroendocrine origin, which are normally present throughout the
GI mucosa
• Constitute about 2% of colorectal malignancies and almost half of the small intestinal
malignant tumours
• Release peptide and nonpeptide hormones, which are responsible for their clinical
manifestations
• Usually arise in the pancreas, peripancreatic tissue, lungs, biliary tree and liver. In the
GIT, appendix is the most common site followed by ileum, rectum, stomach and colon.
• No age is exempt, peak incidence during sixth decade
• Cut surface is solid and yellow-tan.
• The tumour cells have argentaffin granules which stain positive with silver stains.
• Carcinoids are slow-growing tumours with different characteristics and growth patterns
and can be subdivided based on the following features:
• Growth pattern (trabecular, glandular, undifferentiated and mixed)

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