The Cytodiagnosis of Amelanotic Primary Signet Ring Cell Melanoma at the Unusual Site of the Axilla: A Case Report of a Rare Entity.

Amelanotic primary signet ring cell melanoma is a rare variant of cutaneous malignant melanoma. The diagnosis of amelanotic primary signet ring cell melanoma is rarely made based on cytological examinations. Most of the cases reported in the routine practice involve metastatic lesions of known cutaneous amelanotic primary signet ring cell melanoma. The diagnosis of amelanotic primary signet ring cell melanoma on fine needle aspiration cytology (FNAC) is scarce. We present one such extremely rare diagnosis of amelanotic primary signet ring cell melanoma at the unusual site of the axilla, which was established on FNAC. We also discuss its histological differential diagnosis and confirmative immunohistochemistry (IHC).