Cytopathologic features of an unusual case of multiple eccrine spiradenomas misdiagnosed as a malignant round cell tumor.

A 28-year-old lady presented with multiple swellings in her left shoulder, associated with intermittent pain since last one and a half years. Radiologic imaging revealed multiple, well-defined, subcutaneous lesions in her left supraclavicular region. Fine needle aspiration cytology (FNAC) smears were initially reported as Ewing sarcoma, elsewhere. On review, the smears showed cohesive clusters of round-to-oval cells with scant cytoplasm, which were focally arranged in an acinar-rosetting pattern around hyaline "droplets/bodies," along with few scattered lymphocytes against a background of red blood cells. The diagnosis considered was adnexal tumor. Subsequent biopsy from the multiple lesions confirmed the diagnosis of eccrine spiradenoma. By immunohistochemistry, tumor cells were positive for CK7, epithelial membrane antigen (focally), S100 protein, and tyrosine-protein kinase Kit(C-KIT) /Cluster of differentiation (CD117). This case underscores the value of FNAC in skin adnexal tumors and constitutes as the first case report of multiple eccrine spiradenomas, initially misdiagnosed as Ewing sarcoma. Literature review of similar reported cases with treatment implications are presented.