BACKGROUND: Amelanotic melanoma can mimic a wide variety of epithelial and nonepithelial malignant tumors. Varied cytomorphology of melanoma has been described on exfoliative and fine needle aspiration cytology (FNAC). We report a case of recurrent amelanotic melanoma to highlight its varied cytomorphologic features, which may cause diagnostic problems on cytologic and on histologic examinations. CASE: A 63-year-old male presented with nodular swellings in the right anterior chest wall, right axilla and back. A nodule in the chest had been excised 6 months earlier. Clinically, the lesion was interpreted as recurrent soft tissue sarcoma. FNAC revealed malignant cells with highly varied morphology with plasmacytoid and pleomorphic malignant cells with occasional fibrocollagenous tissue strands showing adherent neoplastic cells. A cytologic diagnosis of pleomorphic malignant tumor was suggested, and the original histologic slides were reviewed; they showed a striking alveolar pattern that vaguely resembled an alveolar rhabdomyosarcoma. However, on immunohistochemistry, the tumor cells were S-100 and melan-A positive and desmin negative. A final diagnosis of amelanotic melanoma was made. CONCLUSION: Awareness of the highly varied cytomorphology of amelanotic melanoma minimizes the diagnostic difficulty on fine needle aspiration smears. Suitable immunohistochemical markers are of great value in difficult situations.
BACKGROUND:Amelanotic melanoma can mimic a wide variety of epithelial and nonepithelial malignant tumors. Varied cytomorphology of melanoma has been described on exfoliative and fine needle aspiration cytology (FNAC). We report a case of recurrent amelanotic melanoma to highlight its varied cytomorphologic features, which may cause diagnostic problems on cytologic and on histologic examinations. CASE: A 63-year-old male presented with nodular swellings in the right anterior chest wall, right axilla and back. A nodule in the chest had been excised 6 months earlier. Clinically, the lesion was interpreted as recurrent soft tissue sarcoma. FNAC revealed malignant cells with highly varied morphology with plasmacytoid and pleomorphic malignant cells with occasional fibrocollagenous tissue strands showing adherent neoplastic cells. A cytologic diagnosis of pleomorphic malignant tumor was suggested, and the original histologic slides were reviewed; they showed a striking alveolar pattern that vaguely resembled an alveolar rhabdomyosarcoma. However, on immunohistochemistry, the tumor cells were S-100 and melan-A positive and desmin negative. A final diagnosis of amelanotic melanoma was made. CONCLUSION: Awareness of the highly varied cytomorphology of amelanotic melanoma minimizes the diagnostic difficulty on fine needle aspiration smears. Suitable immunohistochemical markers are of great value in difficult situations.