The value of bone marrow biopsy for staging of patients with primary CNS lymphoma.

Background In patients with presumed primary CNS lymphoma (PCNSL) a systemic manifestation is found only in a small minority. Although bone marrow biopsy (BMB) is recommended for staging, its diagnostic value is unclear. Methods A retrospective analysis of 392 patients with presumed PCNSL from three university hospitals and 33 patients with secondary CNS lymphoma (SCNSL) and initial CNS involvement from a multicentre Germany-wide prospective registry was performed. Results A BMB was performed and documented in 320/392 patients with presumed PCNSL; 23 had pathologic results. One harboured the same lymphoma in the brain and bone marrow (BM), 22 showed findings in BM discordant to the histology of brain lymphoma; n=12 harboured a low grade lymphoma in the bone marrow, the other showed B-cell proliferation but no proof of lymphoma (n=5), monoclonal B-cells (n=3) or abnormalities not B-cell associated (n=2). In the group of SCNSL with initial CNS manifestation 32/33 patients underwent BMB; seven were documented with bone marrow involvement (BMI); one had concordant results in the brain and bone marrow with no other systemic manifestation. Six had additional systemic lymphoma manifestations apart from the brain and bone marrow. Conclusions In only two out of 352 (0.6%) patients with CNS lymphoma (320 presumed PCNSL and 32 SCNSL) BMB had an impact on diagnosis and treatment. While collected in a selected cohort these findings challenge the value of BMB as part of routine staging in presumed PCNSL.