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Case 467 - Discussion

Uploaded: 2010-02-10, Updated: 2011-02-10


Rectal Carcinoid Tumor

  • Most common site of colonic carcinoid is rectum

  • Gross: usually < 5 mm, round, no ulceration

  • Morphology

    • Islands, trabeculae, glands or sheets of monotonous cells.

    • Scant, pink granular cytoplasm and round-oval stippled nuclei, small nucleoli.

    • Minimal pleomorphism, minimal mitotic activity; rarely mucin secretion or anaplasia; no necrosis

  • Positive stains: chromogranin, synaptophysin, neuron specific enolase, PAP (80%), CEA, hCG

  • Negative stains: PSA

  • DDX: prostate carcinoma (PSA+, neuroendocrine markers-)

  • 5 year survival 90%. Poor prognosis: 2 cm or larger, invasion of muscularis propria, 2+ mitotic figures/HPF, angiolymphatic invasion, anaplasia.

  • Treatment: local excision; partial colectomy if malignant potential.