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Erschienen in:
19.09.2019 | The Last Image
A dark polyp in the anorectum
Erschienen in: Techniques in Coloproctology | Ausgabe 11/2019
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Anorectal malignant melanomas (AMM) are rare neoplasms with aggressive behavior, accounting for 0.1%–4.6% of anal canal tumors and less than 2% of all melanomas. A 78-year-old woman, with unexplained rectal bleeding underwent colonoscopy which revealed a pigmented polypoid lesion in the anal canal—snare polypectomy was performed. The histological diagnosis was AMM. Pelvic magnetic resonance imaging was negative. The patient had abdominoperineal resection and definitive histology was negative for residual disease. The patient is alive after 5 years of follow-up (Figs. 1, 2, 3).
Fig. 1
The endoscopic view of a dark necrotized anorectal polyp close to the dentate line, 15 mm in diameter
Fig. 2
Snare polypectomy
Fig. 3
a Histology showing an AMM with a submucosal pigmented lesion, H&E, original magnification 10x. b The specimen: on the left side dark-brown pigment clusters between the cells and in the right side neoplastic cells are organized in solid, demarcated areas, H&E, original magnification 20x. c, d Neoplastic proliferation of cells under the mucosal layer, with large vesicular nuclei, irregular nuclear borders, condensed chromatin, and numerous atypical mitoses; H&E, magnification 20x
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