RESUMEN
Objective: To study the clinicopathological characteristics, and further understand primary central nervous system T-cell lymphoma (PCNSTCL) in children and adolescents. Methods: Five cases of PCNSTCL in children and adolescents were collected from December 2016 to December 2021 at the First Affiliated Hospital of Zhengzhou University. The clinicopathological characteristics, immunophenotypic, and molecular pathologic features were analyzed, and relevant literatures reviewed. Results: There were two male and three female patients with a median age of 14 years (range 11 to 18 years). There were two peripheral T-cell lymphomas, not otherwise specified, two anaplastic large cell lymphoma, ALK-positive and one NK/T cell lymphoma. Pathologically, the tumor cells showed a variable histomorphologic spectrum, including small, medium and large cells with diffuse growth pattern and perivascular accentuation. Immunohistochemistry and in situ hybridization showed CD3 expression in four cases, and CD3 was lost in one case. CD5 expression was lost in four cases and retained in one case. ALK and CD30 were expressed in two cases. One tumor expressed CD56 and Epstein-Barr virus-encoded RNA. All cases showed a cytotoxic phenotype with expression of TIA1 and granzyme B. Three cases had a high Ki-67 index (>50%). T-cell receptor (TCR) gene rearrangement was clonal in two cases. Conclusions: PCNSTCL is rare, especially in children and adolescents. The morphology of PCNSTCL is diverse. Immunohistochemistry and TCR gene rearrangement play important roles in the diagnosis.