Granulomatous lesions in bone marrow: Clinicopathologic findings and significance in a study of 48 cases

PurposeGranulomas in bone marrow are an infrequent finding related to various disorders. The aim of this study was to review our clinical experience with granulomatous bone marrow disease and to describe the contributions of recent diagnostic tools, such as 18F-Fluorodeoxyglucose positron emission tomography (18F-FDG-PET) and molecular biology.MethodsClinical, laboratory and morphological data on patients with a granuloma based on bone marrow biopsy analysed in the University Hospital Lyon from May 2004 to July 2010 were reviewed.ResultsWe identified 57 cases among 9641 bone marrow biopsies, representing an incidence of 0.59% in the series and an annual incidence of 9.5 cases per year. Nine biopsies performed for staging a known pathology were excluded from further analysis. Among the 48 remaining patients, associated disease was demonstrated in 79%, with infections being the most common (33%), following by sarcoidosis (21%), malignancy (19%) and therapy-induced granulomas (6%). One previously unpublished entity is described: infection with Bartonella henselae diagnosed using molecular biology from node and skin biopsies in two renal transplant patients. 18F-FDG-PET, performed in 13 cases, showed hypermetabolic foci consistent with sarcoidosis in two cases. Positive PCR result for an infectious pathogen was obtained in three bone marrow samples (Mycobacterium tuberculosis, n = 1; Mycobacterium genavense, n = 2).ConclusionIn comparison to previous research, our study reports high proportions of cases caused by sarcoidosis and unknown causes. 18F-FDG-PET could show signs consistent with sarcoidosis and molecular biology is useful for the detection of fastidious bacteria in immunocompromised patients.