Primary non-Hodgkin's lymphoma of bone: a clinicopathological investigation of 60 cases.

A retrospective analysis of patients presenting with primary lymphoma of bone (PLB) was performed to determine clinical factors affecting prognosis in relation to histological subtype and treatment outcome. Data from 106 patients, presenting with a PLB between 1943 and 1996, were retrieved from the files of the Netherlands Committee on Bone Tumours and Leiden University Medical Centre. The lymphomas were reclassified according to the REAL and updated Kiel classification. The clinical presentation, survival and prognostic factors were investigated. Sixty patients had sufficient clinical information and adequate follow-up to be included in the study. All 33 PLB that could be immunophenotyped were of B cell origin. According to the REAL classification, most PLB were large (B) cell lymphomas (92%) and according to the Kiel classification 45% of the tumours were centroblastic multilobated. PLB presented most often in the long bones (48%), with Ann Arbor stage I (46%), II (16%), IV (16%) and unknown (20%). Stage IV disease was exclusively caused by the presence of multiple bone lesions. Notwithstanding the heterogeneous treatment, the 5-year overall survival was 61%; 46% of patients were progression free at 5 years. Patients at presentation older than 60 had a worse overall survival (76% vs 37%, P = 0.0002) and a worse progression-free period (58% vs 28%, P = 0.0073). Patients with the immunoblastic subtype had a worse survival than the centroblastic mono/polymorphic subtype or the centroblastic multilobated subtype (P = 0.015). Primary lymphoma of bone represents an uncommon bone tumour with a relatively homogeneous morphology and clinical behaviour. Compared to other aggressive lymphomas, PLB have a favourable prognosis.