Indolent T-lymphoblastic proliferation concomitant with acinic cell carcinoma mimicking T-lymphoblastic lymphoma: case report and literature review.

AIMS: Indolent T-lymphoblastic proliferation (iT-LBP) is a non-clonal benign condition showing extrathymic proliferation of T-lymphoblasts positive for CD3, CD4, CD8, and TdT. Isolated iT-LBP has been observed, but the majority of iT-LBPs have been seen in conjunction with other disorders, including Castleman disease, hepatocellular carcinoma, follicular dendritic cell tumours, angioimmunoblastic T-cell lymphoma, myasthenia gravis, and acinic cell carcinoma (ACC). The clinical course of iT-LBP is indolent, and no therapy is usually required. A major concern is misdiagnosis as T-lymphoblastic lymphoma, and a correct diagnosis of iT-LBP often requires not only pathological analysis but also careful monitoring of the clinical course. The aim of this study was to broaden the knowledge of pathologists and physicians concerning this as yet not well-recognised entity.

METHODS AND RESULTS: We report a case of iT-LBP concomitant with ACC, along with a literature review of all 14 cases of iT-LBP reported to date.

CONCLUSIONS: iT-LBP should always be considered as a differential diagnosis of T-lymphoblastic lymphoma, as the two disorders show extremely similar traits.