Colon tumor - Carcinoid-rectum

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Colon tumor

Carcinoid tumors

Carcinoid-rectum

Reviewers: Charanjeet Singh, M.D. (see Reviewers page)
Revised: 21 February 2012, last major update January 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Most common site of colonic carcinoid is rectum
● Annual incidence in USA: 10 per million vs. 500 per million for adenocarcinoma (Int J Colorectal Dis 2007;22:183)
● Rarely is familial (Tech Coloproctol 2006;10:143)
● 5 year survival is 90% (Cancer 2003;97:934)
● Prognosis: higher TNM stage and presence of lymphovascular invasion are associated with lower survival (Int J Colorectal Dis 2010;25:1087)
● Poor prognosis (malignant potential): 2 cm or larger (associated with nodal metastases), invasion of muscularis propria, 2+ mitotic figures / HPF, angiolymphatic invasion and anaplasia

Case reports
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● Liver metastases from tumor less than 5 mm (Hepatogastroenterology 2004;51:1330)
● Incidental finding on prostatic needle core biopsy (Hum Pathol 2010;41:1674)
● 43 year old man with minute liver metastases (World J Gastrointest Surg 2010;2:89)
● 55 year old man with lifelong ulcerative colitis and atypical carcinoid (J Clin Pathol 1986;39:913)

Treatment
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● Local excision (J Laparoendosc Adv Surg Tech A 2006;16:435)
● Partial colectomy if malignant potential (see above)

Gross description
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● Usually 5 mm or less, round and no ulceration

Micro description
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● Islands, trabeculae, glands or sheets of monotonous cells with scant, pink granular cytoplasm and round-oval stippled nuclei, small nucleoli, minimal pleomorphism and minimal mitotic activity
● Rarely mucin secretion or anaplasia; no necrosis

Micro images
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Submucosal tumors


Various images


Chromogranin+


Atypical carcinoid (left to right): H&E, angiolymphatic and perineural invasion, synaptophysin

Positive stains
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● Chromogranin, synaptophysin and neuron specific enolase
● Also PAP (80%), CEA, hCG and PAX-8

Negative stains
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● PSA

Electron microscopy description
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● Cytoplasmic, well-formed membrane bound secretory granules with dense (osmophilic) cores

Molecular description
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● Diploid if non-metastasizing, aneuploid if metastatic

Differential diagnosis
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● Prostatic adenocarcinoma: PSA+, neuroendocrine markers-
● Metastatic disease: PAX8 is absent in ileal/pulmonary carcinoids but positive in rectal carcinoid tumors (Am J Surg Pathol 2010;34:723)

Additional references
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● eMedicine

End of Colon tumor > Carcinoid tumors > Carcinoid-rectum

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