The American journal of surgical pathology. vol:26 issue:7 pages:938-44
We report a case of a primary cutaneous alveolar rhabdomyosarcoma presenting on the lower limb of a 60-year old woman. The tumor was characterized by aggregates of round blue cells in an alveolar growth pattern in the dermis and subcutis, with the additional unique finding of epidermotropism. By immunohistochemistry tumor cells were positive for vimentin, muscle-specific actin, desmin, myogenin, and Myo-D1 with focal positivity for CD56, neuron-specific enolase, and S-100 protein. Staining for pan-keratin, HMB-45, melan-A, epithelial membrane antigen, chromogranin, CD99, leukocyte common antigen, and alpha-smooth muscle actin was negative. Interphase fluorescence in situ hybridization analysis from paraffin-embedded tumor demonstrated the presence of the translocation (2;13)(q35;q14) confirming the diagnosis. Further investigations revealed no tumor in the underlying deep soft tissues, and there was no evidence of metastasis in other organs. A local recurrence associated with a metastasis to a regional lymph node on the right groin was treated with an above-knee amputation and local radiotherapy to the groin area. The patient subsequently developed cutaneous metastases in the amputation stump and died 2 years after initial presentation. This case indicates that rhabdomyosarcoma may rarely present in the skin in adults and should be included in the differential diagnosis of primary cutaneous small round blue cell tumors not only in children but also in this age group.