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Germinal centers in the bone marrow
1Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106.
Germinal centers (GCs) in the marrow have been described, but not systematically studied. Twelve cases from the axial skeleton from patients aged 29-80 years were examined. The male female ratio was 1:5, and the yearly incidence was 0.8% of bone marrow specimens. Most patients were anemic (mean hematocrit 34%); five had eosinophilia. When both clots and core biopsies were obtained, GCs were found more often in clots. Associated lymphoid aggregates were evident in 60% but no patient fulfilled criteria for nodular lymphoid hyperplasia. GCs coexisted in one case with malignant lymphoma. Polyclonal plasmacytosis was present in 40% of the cases. Scattered T cells, ringing the GC, were identified in most cases. S-100 staining demonstrated a peripheral nerve associated with one GC. Marrow GCs have been considered a reaction to splenectomy and a forerunner of malignant lymphoma; neither theory is supported in these cases. The findings raise the possibility of immune function by the marrow in adults, possibly akin to follicular hyperplasia in the spleen.
Germinal centers (GCs) in the marrow have been described, but not systematically studied. Twelve cases from the axial skeleton from patients aged 29-80 years were examined. The male female ratio was 1:5, and the yearly incidence was 0.8% of bone marrow specimens. Most patients were anemic (mean hematocrit 34%); five had eosinophilia. When both clots and core biopsies were obtained, GCs were found more often in clots. Associated lymphoid aggregates were evident in 60% but no patient fulfilled criteria for nodular lymphoid hyperplasia. GCs coexisted in one case with malignant lymphoma. Polyclonal plasmacytosis was present in 40% of the cases. Scattered T cells, ringing the GC, were identified in most cases. S-100 staining demonstrated a peripheral nerve associated with one GC. Marrow GCs have been considered a reaction to splenectomy and a forerunner of malignant lymphoma; neither theory is supported in these cases. The findings raise the possibility of immune function by the marrow in adults, possibly akin to follicular hyperplasia in the spleen.