title: Germinal centers in the bone marrow.
abstract: 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.
authors.affiliation: Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106.
authors.forename: D C
authors.initials: DC
authors.lastname: Farhi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000740:Anemia / Q000473:pathology*; D001706:Biopsy; D001853:Bone Marrow / Q000473:pathology*; D002449:Cell Aggregation / Q000502:physiology; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000166:cytology*; D008223:Lymphoma / Q000473:pathology; D008232:Lymphoproliferative Disorders / Q000473:pathology; D008297:Male; D008875:Middle Aged; D013156:Splenectomy / Q000009:adverse effects