Indolent T-lymphoblastic proliferation: report of a case with a 16-year course without cytotoxic therapy.

T-lymphoblastic lymphoma is a high-grade malignant lymphoma. Clinically indolent T-lymphoblastic proliferations have not been described. We present a case report of an indolent T-cell lymphoblastic proliferation studied by histopathology, immunohistochemistry, flow cytometry, antigen receptor gene rearrangement studies, and cytogenetics. The patient had recurrent masses in the upper aerodigestive tract over a 16-year period, was treated by multiple surgical excisions, and never received either chemotherapy or radiotherapy. A proliferation of lymphoblasts was present histologically. The cells were positive for terminal deoxynucleotidyl transferase, CD1, and CD3, and coexpressed CD4 and CD8. No clonal rearrangements of the T-cell receptor beta or gamma chain genes were identified. Cytogenetic studies revealed a questionable inversion of the short arm of chromosome 9, affecting the 9p21-22 region. Although ectopic thymic tissue was considered, the case was considered to be an indolent lymphoblastic proliferation. It should be recognized that rare lymphoblastic proliferations may not behave in a high grade fashion as typically seen in T-lymphoblastic lymphoma.