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Anorectal malignant melanoma: morphologic and immunohistochemical features
Deborah J Chute1, John B Cousar, Stacey E Mills
1Department of Pathology, University of Virginia Health System, Charlottesville, VA 22908, USA.
American Journal of Clinical Pathology
|June 7, 2006
Summary
Primary anorectal malignant melanoma exhibits diverse morphology and staining patterns, similar to skin melanomas. No specific features predicted patient survival in this review.
Area of Science:
- Gastrointestinal Pathology
- Dermatopathology
- Oncology
Background:
- Primary anorectal malignant melanoma is a rare tumor.
- Understanding its morphologic and immunohistochemical features is crucial for diagnosis.
Purpose of the Study:
- To analyze the morphologic and immunohistochemical characteristics of primary anorectal malignant melanoma.
- To assess the predictive value of these features on patient survival.
Main Methods:
- Review of 17 primary anorectal malignant melanoma cases.
- Evaluation of morphologic features: junctional change, pigmentation, morphology, and mitotic rate.
- Immunohistochemical staining for S-100 protein, HMB-45, MelanA, tyrosinase, vimentin, KIT, and pankeratin.
Main Results:
- Significant morphologic variability observed, including epithelioid, spindle cell, lymphoma-like, and pleomorphic subtypes.
- Immunohistochemical profile generally consistent with cutaneous melanomas, with S-100 protein present in all cases.
- KIT expression was frequent, particularly in spindle cell variants, posing a potential diagnostic challenge with gastrointestinal stromal tumors.
Conclusions:
- Anorectal malignant melanoma displays considerable morphologic diversity.
- Immunohistochemical findings are comparable to cutaneous melanomas.
- No specific morphologic or immunohistochemical markers were found to predict survival in this cohort.
