Primary mediastinal large B-cell lymphoma with sclerosis in pediatric and adolescent patients: treatment and results from three therapeutic studies of the Berlin-Frankfurt-Münster Group.

Abstract

Primary mediastinal large B-cell lymphoma with sclerosis (PMLBL) is a rare entity of non-Hodgkin's lymphoma (NHL) arising from thymic mature B cells. Optimal treatment strategies remain to be established, especially in pediatric patients. This study analyzes clinical characteristics and treatment outcome of 30 pediatric patients with PMLBL, diagnosed in multicenter therapy NHL-Berlin-Frankfurt-Münster Group (BFM) trials. Treatment was stratified by stage and serum lactate dehydrogenase (LDH) and consisted of four to six 5-day courses of chemotherapy using steroids, oxazaphosphorine alkylating agents, methotrexate, cytarabine, etoposide, and doxorubicin. Radiation was not part of the protocol. From April 1986 to August 1999, 1,650 patients with newly diagnosed NHL were enrolled in the NHL-BFM trials; 30 patients (1.8%) had PMLBL. Median age was 14.3 years (range, 1.4 to 16.7 years); 15 patients were male and 15 patients were female. With a median observation time of 5 years (range, 1 to 12 years), probability of event-free survival (pEFS) at 5 years was 0.70 (SE, 0.08). Two patients erroneously diagnosed as T-cell NHL received non-B-cell therapy and died from progress of disease. Events in 28 patients receiving B-cell therapy included early progress during therapy (n = 1) and relapse (n = 6). Residual mediastinal masses were present in 23 patients after two courses of therapy and in 15 patients after the end of therapy. LDH > or = 500 U/L was associated with increased risk of failure in multivariate analysis. PMLBL mainly is found in adolescents. Dose-intense chemotherapy including high-dose methotrexate yields a pEFS at 5 years of 0.70 (SE, 0.08). LDH is of prognostic value in pediatric patients with PMLBL.