RT Journal Article SR Electronic T1 Primary lymphoma of bone: extranodal lymphoma with favourable survival independent of germinal centre, post-germinal centre or indeterminate phenotype JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 820 OP 824 DO 10.1136/jcp.2008.063156 VO 62 IS 9 A1 F H Heyning A1 P C W Hogendoorn A1 M H H Kramer A1 C T Q Holland A1 E Dreef A1 P M Jansen YR 2009 UL http://jcp.bmj.com/content/62/9/820.abstract AB Aims: To determine prognostic significance of immunohistochemical markers and investigate possible germinal centre (GC) derivation in primary lymphoma of bone (PLB).Methods: Immunohistochemical expression of BCL-6, CD10, BCL-2, p53, CD30, CD44 and MUM-1 was studied in 36 patients with PLB. All cases were clinically staged and cases of secondary bone involvement of primary nodal lymphomas were excluded, prior to immunostaining. Clinical charts were reviewed for clinical symptoms and therapy given; survival post-biopsy was calculated.Results: All patients presented with pain and a palpable mass. The majority showed centroblastic-multilobated morphology; half of the cases (19/36) had a GC phenotype (CD10+BCL-6+ or CD10−BCL-6+MUM-1−), whereas 8/36 cases had a non-GC phenotype (CD10−BCL-6− or CD10−BCL-6+MUM-1+). Nine cases were of indeterminate phenotype (CD10−BCL-6+; MUM-1 not available). Eight of 22 evaluated patient samples showed immunoreactivity for MUM-1. Most patients (31/36) received combination therapy in the form of polychemotherapy and radiotherapy. The five-year overall survival was 75%. No significant difference in survival was found between the three different tumour phenotypes, or for the tested antigens individually. Age at presentation and stage of disease had a significant influence on five-year overall survival. Survival rates were 90% for the patients <60 years of age and 40% for those ⩾60 years. Survival rates were 90% for stage I and 41% for stage IV.Conclusion: This study illustrates the homogeneity of PLB. The majority of cases are of the GC phenotype which has a favourable prognosis.