Primary malignant lymphoma arising in postmastectomy lymphedema. Another facet of the Stewart-Treves syndrome.

In rare cases, primary malignant lymphomas may arise in the soft tissues. Only one previous case has arisen in the context of chronic lymphedema. Because of the clinical appearance of such lesions, which resemble violaceous nodular or plaquelike tumors, they may be confused clinically with lymphedema-associated angiosarcomas occurring after radical mastectomy (Stewart-Treves syndrome). Furthermore, the histologic appearance of some lymphomas and angiosarcomas may also be similar. We studied two women with primary postmastectomy lymphedema-related malignant lymphoma in the soft tissues of the upper arm. These tumors arose 11 and 30 years, respectively, after radical removal of ductal mammary carcinomas. Histologically, one neoplasm mimicked metastatic carcinoma or epithelioid angiosarcoma; whereas the other was initially confused with a variety of pathologic entities, including vasculitis, epithelioid hemangioma, and malignant fibrous histiocytoma. The lymphoid nature of both lesions was confirmed by immunoreactivity for leukocyte common antigen in addition to the B-lymphocyte marker, L26. Conversely, vascular and epithelial determinants were absent. One patient's disease pursued an indolent course; she died of unknown causes but with no evidence of lymphoma at last follow-up. The second patient is currently in remission on chemotherapy. Awareness of the existence of lymphedema-related malignant lymphoma and familiarity with methods used for its distinction from epithelioid vascular sarcomas should prevent unnecessary surgery.