Precursor B lymphoblastic lymphomas (B-LBL) are generally rare, but appear to have a higher incidence in children than in adults. In this report, we describe in detail six cases of B-LBL presenting with cutaneous lesions. Three occurred in the scalp, one in the skin of the thigh, one in the skin of the face and breast, and one in the subcutaneous tissue of the orbit. All six patients are females ranging in age at presentation from 5 to 15 years (mean = 9.6). None of the cases had bone marrow involvement, while two had bone involvement (maxilla, distal tibia, and distal humerus in one case, and distal tibia and orbital bone in another case); only one case had lymphadenopathy (retroperitoneal). Immunohistochemical staining showed positivity for CD79a and CD43 in all six cases. LCA and L26 positivity were also each seen in one case. Staining for MIC-2 (CD99) showed strong positivity in three cases. Vimentin was positive in four cases and TdT was positive in all five patients tested. Staining for keratin, UCHL-1, or CD30 was not encountered. Cases in which cell marker studies by flow cytometry were performed showed positivity for CD10, CD19 with negative CD20, pan-T-cell, and myeloid markers. The five patients who received multiagent chemotherapy are alive with follow-up intervals of 2 to 18 years. Two patients had local recurrences and were given radiation therapy (one with repeating multiagent chemotherapy). One patient (diagnosed in 1962) died of disseminated disease; she had been treated with radiation therapy and 6MP only. Cutaneous B-LBL must be included in the differential diagnosis of small blue cell tumors, especially in children. In contrast to its T-cell counterpart, B-LBL occurs more frequently in females, tends to present as skin or bone lesions, and is associated with a potential cure, even in cases that relapse.
T-cell lineage determination