Characteristics and Clinical Implications of Reactive Germinal Centers in the Bone Marrow

Publication date: Available online 17 April 2017
Source:Human Pathology
Author(s): Rose Lou Marie C. Agbay, L. Jeffrey Medeiros, Joseph D. Khoury, Alireza Salem, Carlos E. Bueso-Ramos, Sanam Loghavi
Reactive germinal centers (GCs) in the bone marrow (BM) have been described in patients with autoimmune disorders, infections, malignancies and following certain drug therapies, or as an isolated finding without obvious underlying disease. In this study, we describe the clinical conditions in which reactive GCs occur in BM samples, and their topography and accompanying laboratory and ancillary findings in the setting of a cancer center. We identified 32 BM specimens with reactive GCs with an estimated frequency of <0.02% over a 12year period. Fifteen (46.9%) BM specimens had concurrent hematolymphoid neoplasms: most often a variety of small B-cell lymphomas, but also myelodysplastic syndromes. One (3.1%) case was involved by metastatic melanoma. Isolated reactive GCs were observed in 16 (50%) patients. Most BM specimens (n=25, 78.1%) showed only one reactive GC with a size ranging from 20 to 500μm and most GCs (29/32) were nonparatrabecular. GCs were positive for CD10 and Bcl-6, and were negative for Bcl-2. CD3 and CD5 demonstrated T-cells surrounding the germinal center, CD21 and CD23 highlighted follicular dendritic cells. Reactive germinal centers are uncommon and can be seen in association with hematolymphoid and other types of neoplasms or as an isolated finding. Reactive GCs are usually located in a nonparatrabecular distribution. A panel of immunohistochemical (IHC) stains is useful to confirm the non-neoplastic nature of these germinal centers to avoid misdiagnosis as lymphoma or as histologic evidence of transformation in a patient with small B-cell lymphoma in the bone marrow.



http://ift.tt/2pNwA9R