This lymphoma arose in a 22-year-old immunocompetent male with an isolated mediastinal mass, showed MGZL-like morphology and immunophenotype (strong CD30 and CD20 expression; negative for CD15, CD79a, OCT2, and BOB1), and demonstrated a PMBL-like GE with Lymph3Cx analysis (Fig. 4A; Fig. 8A–E). The gene discussed is TNFRSF8; the disease is lymphoma.