Inflammatory disorders of bone marro.

Inflammatory lesions in bone marrow, observed during a 2 year period at the College of Veterinary Medicine, University of Minnesota, were reviewed. Of 24 bone marrow specimens with evidence of inflammation, six were classified as acute inflammation, nine as fibrinous inflammation, five as chronic inflammation/hyperplasia, three as granulomatous inflammation and one as nodular lymphoid hyperplasia. Acute inflammation commonly accompanied bacterial sepsis. Two patterns of acute inflammation were identified. One pattern consisted of multifocal microabscesses. The other pattern of acute inflammation consisted of perivascular infiltrates of neutrophils, fibrin, edema, and hemorrhage. The most common disorder associated with fibrinous inflammation was disseminated intravascular coagulopathy. Chronic inflammation was difficult to differentiate from chronic immune stimulation. Discrete granulomas were identified in the marrow of animals with systemic mycotic disease, idiopathic systemic granulomatous disease, and serous atrophy of fat. This study indicates that a broad variety of inflammatory disorders occur in animal bone marrow and that these disorders can be classified based on general categories of inflammation described in other tissues.