Rhabdoid melanoma: A diagnostic ordeal

A 64-year-old man presented with multiple, bilateral pulmonary nodules, considered clinically to be intrapulmonary metastasis from lung carcinoma. On histopathologic examination, a tumor with a solid growth pattern and rhabdoid neoplastic morphology was seen. Initially, a diagnosis of nonsmall cell carcinoma of lung was considered but the immunophenotype was not supportive. Further, extensive immunohistochemistry revealed SOX10, Melan-A, and HMB45 expression in the absence of S-100. Strong globular cytoplasmic staining for vimentin, SMA, Desmin, and WT1 were observed. A final diagnosis of rhabdoid melanoma was made. The immunoprofile of our case was unique from previously described rhabdoid melanoma in English literature. The globular staining for intermediate filaments such as desmin and SMA is a novel finding. The strong WT1 intracytoplasmic staining reported previously was also observed in this case, with intense globular characteristics.