Subcutaneous T-cell lymphoma: a clinical, histopathologic, and immunohistochemical study of six cases.

Recently, T-cell lymphoma localized to the subcutaneous tissue has been reported. We report the clinical, histologic, immunohistochemical, and molecular genetic findings in 6 patients who we believe had this peculiar T-cell lymphoma with its unique morphologic and clinical features. All patients presented with deep-seated nodules, most frequently on the extremities, and with systemic complaints of low-grade fever, fatigue, myalgias, and weight loss. In all cases, the neoplastic lymphocytic infiltrate was confined to the subcutaneous tissue, predominantly in a lobular pattern. Hemorrhage, necrosis, and rare erythrophagocytosis were also seen. Immunohistochemical staining was predominantly T-cell reactive (CD43, CD3, and CD45RO). Clonal rearrangements of the beta and gamma chains of the T-cell antigen receptor genes were found in 1 case. Three of the 6 patients died within 22 months of the diagnosis of lymphoma. We believe that subcutaneous T-cell lymphomas are a distinctive group of peripheral T-cell lymphomas with unusual clinical and morphologic features and that they should be distinguished from other types of lymphoma.