Preferential Cutaneous Infiltration by Neoplastic Thymus-Derived Lymphocytes

Abstract

The abnormal lymphocytes from three patients with mycosis fungoides and from four patients with lymphocytic leukemia accompanied by exfoliative erythroderma were shown to have membrane properties of thymus-derived lymphocytes (T cells).

Several other significant features were identified in the four patients with lymphocytic leukemia. The neoplastic lymphocytes from three patients had morphologic characteristics of the "small cell variant" of the Sézary cell. Cells from the other patient had both bone marrow-derived (B)- and T-cell markers. T cells from two patients were essentially unresponsive to mitogens, and one patient's lymphocytes failed to stimulate allogeneic normal lymphocytes in mixed leukocyte cutures, despite the presence of histocompatability antigens. The abnormal, circulating T cells in each of the four leukemic patients not only preferentially infiltrated the skin but remarkably spared the bone marrow. These findings suggest that lymphoproliferative disorders with widespread cutaneous infiltration are frequently T-cell malignancies with several distinguishing cellular features.