Lymphoblastic lymphoma presenting in cutaneous sites. A clinicopathologic analysis of six cases.

Six patients with malignant lymphoma of lymphoblastic type involving cutaneous sites at time of diagnosis are presented. Skin sites of the head and neck were involved in all patients and included the scalp (three patients), forehead (two patients), and malar region of the face (one patient). Two patients also had additional sites of skin disease (neck, breast, and anterior trunk). In two patients the skin was the predominant site of disease, whereas in the remaining patients staging workup revealed generalized lymphoma. The histologic findings in each patient were typical of lymphoblastic lymphoma; the neoplastic cells were small with blastic nuclear chromatin. In three patients the neoplastic cells were convoluted, and in three they were nonconvoluted. Immunophenotypically, four lymphomas were of pre-B cell type, and two lymphomas were of T cell type. There was no correlation between histologic features and the immunophenotype. Since the majority of lymphoblastic lymphomas are of T cell type, the predominance of pre-B cell tumors involving the skin may suggest that pre-B cell neoplasms have a predilection for cutaneous involvement. In further support of this hypothesis, both lymphomas that appear to have arisen in the skin had a pre-B cell immunophenotype.