Sarcomatoid variant of anaplastic large-cell Ki-1 lymphoma.

Although anaplastic large-cell Ki-1 lymphomas can mimic a variety of tumors, a correct diagnosis is usually not difficult to reach if it is recognized that lymphoma cells can assume bizarre and pleomorphic appearances and that the pattern of growth can be purely sinusoidal. We report a unique case of a 45-year-old man presenting with a leg lesion that showed sarcomatoid growth patterns. The subcutaneous/dermal tumor displayed a myxoid stroma reminiscent of myxoid malignant fibrous histiocytoma. In a subsequent lymph node biopsy, a well-developed storiform pattern was formed by interweaving fascicles of plump spindle and oval neoplastic cells, reminiscent of pleomorphic/storiform type of malignant fibrous histiocytoma. The lymphoid nature of the tumor cells was documented by immunoreactivity for leukocyte common antigen, Ki-1 antigen, and the T-cell marker UCHL1. We conclude that the presence of a storiform or myxoid pattern does not disqualify the diagnosis of lymphoma; this possibility should always be pursued in pleomorphic tumors because the treatment is substantially different from that for sarcoma, carcinoma, or melanoma.