T-lymphoblastic lymphoma/leukemia without clonal TCR gene rearrangements: case report and literature review.

Abstract

T-lymphoblastic lymphoma (T-LBL) is a highly aggressive malignancy originating from T-lymphocyte precursors. Incidence is highest in children and adolescents. T-cell receptor (TCR) gene rearrangement is usually present. TCR gene rearrangement-negative cases are considered rare. Here, we investigated the clinicopathological features, differential diagnosis, therapy, and prognosis of TCR gene rearrangement-negative T-lymphoblastic lymphoma/leukemia (T-LBL/ALL) by case report and literature review. An 18-year-old male with polyglandular lymphadenopathy underwent an excisional lymph node biopsy and bone marrow aspiration that disclosed diffuse distribution of round, small to medium sized cells with scant cytoplasm, delicate chromatin, and frequent mitotic figures. Immunophenotyping showed expression of TDT, CD3, CD7, and CD5, no CD34, CD20, CD56, bcl-6, CD4, CD8, or MPO in lymph node tissue. Immunohistochemical staining for pathological consultation was performed by Streptavidin peroxidase (SP) method, EB virus coded small RNA (EBER) tested by in situ hybridization (ISH), (EBER-ISH). And flow cytometry of bone marrow aspirate showed that tumor cells expressed CD3, CD5, CD7; partial expression of CD2, CD10, CD38, TDT; and no expression of CD1a, CD34, CD4, CD8, mCD3, CD33, CD56, CD19, CD79a, HLA-DR and MPO. These findings led to the diagnosis of T-LBL/-ALL. Molecular genetic testing showed no TCR gene rearrangement. The patient received chemotherapy consisting of vinorelbine, pirarubicin, cyclophosphamide, asparaginase, and prednisone. Prophylactic chemotherapy of the central nervous system and radiotherapy of the mediastinum were also given. And responded to combined chemotherapy and radiotherapy. Although T-LBL/ALL typically features TCR gene rearrangement, rare cases without rearrangement may occur. Diagnosis is based on clinical characteristics, histopathology, immunotyping, and molecular genetics.