Gross pathology of fibrous dysplasia: The affected bone is expanded. The lesion is well-demarcated and intramedullary. The lesional tissue is dense, fibrous, gritty, and has abnormal-looking tan-gray color. There may be cystic change or dense ossification within the lesion. Case history: This is a specimen of excised left 5th rib. The patient was a 50 y/o male who presented with a firm to hard, non-tender swelling on left side of the chest. Chest X-ray and computed tomography (CT) scan showed a solid (non-lytic) expansile lesion involving the left 5th rib. The excised rib measured 14 cm in length with a 9 cm fusiform expansion in the center. On cut surface, grey-white, firm tissue, replacing medullary cavity is seen with thinning of the cortex. Microscopic examination showed fibrous dysplasia of bone. Image courtesy of: Dr. Sanjay D. Deshmukh, Professor of Pathology, Dr. Vithalrao Vikhe Patil Medical College & Hospital, Ahmednagar, India.