Childhood primary cutaneous non-T/non-B lymphoma followed by acute T-cell leukemia

An 8-year-old girl presented with cutaneous lymphoma without bone marrow or visceral involvement. The tumor cells displayed convoluted and invaginated euchromatic nuclei. The immunophenotype of these cells was non-T/non-B (Ia+, CALLA-, SIg-, TdT-, E-, Thy-). The skin lesions regressed promptly with chemotherapy including cyclophosphamide, vincristine, methotrexate, doxorubicin, and cytosine arabinoside. Six months after the completion of chemotherapy (18 months postdiagnosis), the patient had a relapse of the skin lesions with concurrent bone marrow involvement. The cutaneous infiltrate at relapse was morphologically and immunophenotypically similar to that at the onset of illness. However, the bone marrow infiltrate, although morphologically similar to the cutaneous tumor, had an immunophenotype consistent with T-cells (Ia+, CALLA-, SIg-, E-, TdT+, Thy+, OKT4+, OKT8+). As in adults, primary cutaneous non-T/non-B lymphomas in children may be derived from T-cells or their precursors.