Indolent T-lymphoblastic proliferation: a report of three cases.

Indolent T-lymphoblastic proliferation (iT-LBP) is the extrathymic proliferation of nonclonal TdT + T cells and is typically associated with lymphoid disorders. Although one study revealed that iT-LBP occurred in angioimmunoblastic T-cell lymphoma, no other lymphoma-related cases have been reported. Here, we report three cases of concurrent iT-LBP and benign or malignant lymphoid disorders. The first patient had bilateral cervical lymph node enlargement, and the resected lymph node showed polyclonal precursor T-cells distributed between benign hyperplastic lymphoid follicles. In the second case, iT-LBP occurred in peripheral T-cell lymphoma with a follicular growth pattern, showing that precursor T-cells were distributed between neoplastic follicles composed of CD4 + and CXCL13 + T-cells. In the third case, polyclonal precursor T-cells were distributed between the neoplastic follicles of follicular lymphoma. In summary, our results indicate an association between iT-LBP and reactive lymphoid hyperplasia (case 1) and lymphoma (cases 2 and 3).