Primary lymphoma arising in skeletal muscle.

A case of lymphoma arising primarily from the biceps muscle is reported. While this is an exceedingly rare event, lymphoma may also invade or metastasize to muscle, and should be considered in the differential diagnosis of tumours arising from skeletal muscle. Proper evaluation of a muscle mass includes biopsy with electron microscopy and immunohistochemical studies if the cell type of the tumour is uncertain. Treatment of a muscle mass based on the histologic diagnosis of undifferentiated neoplasm is unacceptable since it may lead to unnecessary radical surgery, while curative nonsurgical therapy is available.