Long bone (femur): Osteomyelitis and arthritis, chronic-active, severe, multifocal, granulomatous and necrotizing
History: Chicken, adult, female
Diagnoses: Long bone (femur): Osteomyelitis and arthritis, chronic-active, severe, multifocal, granulomatous and necrotizing
Description: Multifocally, necrotic areas of variable sizes are present within the bone marrow. Some lesions involve the compact bone of the cortex and the subchondral bone, some with opening into the articular cavity with destruction of hyaline cartilage and subsequent arthritis.
Comments: The chicken presented clinically with severe lameness and restricted mobility in both hip joints. Radiologically, the gizzard was not clearly definable and a tentative diagnosis of neoplasia was made. The animal was euthanized. Pathologic examination revealed large granulomas in several organs including the lungs, spleen and intestine. Long bones were also affected by multifocal to coalescent osteomyelitis and large areas of necrosis. In some joints accumulation of caseous material due to spread of the inflammation from the subchondral bone and resulting arthritis was seen.
Histologically, lesions were characterized by widespread necrosis and chronic granulomatous inflammation with intralesional acid fast and PAS-positive bacteria in macrophages. Findings are consistent with mycobacteriosis due to infection with bacteria from the Mycobacterium avium-intracellulare complex.
Picture by: Kristina Dietert, Department of Veterinary Pathology, Freie Universität Berlin, Germany
Authored by: Olivia Kershaw, Department of Veterinary Pathology, Freie Universität Berlin, Germany