Osteochondroma• Key points: – Common benign bone tumor – Due to displacement of growth plate cartilage to the metaphysis – Points away from the joint – Marrow and cortex are contiguous with the host bone – Cartilaginous cap that shrinks with ageMurphey et al. Radiographics 2000; 20:1407-1434
Osteochondroma• Key points: – Clinical issues • Mass affect on adjacent tissue (bursitis, joint immobility, nerve compression, pseudoaneurysms) • Thicken cartilaginous cap (> 2cm in adults) associated with transformation to chondrosarcoma – DDX • Osteochondroma • Myositis ossificans • Parosteal osteosarcoma • Surface chondrosarcoma • Nora’s lesion (BPOP)
Sarcoidosis – Key points • Granulomatous disease of unknown cause • Non-caseating granulomas affecting multiple organ systems (lungs, lymph nodes, skin, eyes, MSK system) • Sarcoid myositis: – Muscle involvement is common(50-80%) but rarely symptomatic (1-2%) – Presents with muscle weakness and pain – 3 subtypes: nodular, acute myositis, chronic myopathy – Diagnosed by muscle bx and treated with steroidsVardhanabhuti et al. Clin Radiol 2012. 67;263-276
Sarcoidosis – Key points• Bone and Joint involvement: – Can involve small and large bones – “Lacy pattern” of osteolysis in digits with “sausage-like” dactylitis of the fingers on radiographs – MRI can have variable appearance (round, “starry sky pattern”, infiltrative); Low T1 and high T2/STIR
Lipomatosis of Nerve• AKA: fibrolipomatosis hamartoma• Anomalous growth of fibrofatty tissue within a nerve causing fusiform enlargement• Histological changes within the nerve are identical to macrodystrophia lipomatosa• Unknown cause, however, may be due to irritation or compression of nerve• 80% in median nerve (carpal tunnel) and ulnar nerve (cubital tunnel)• Enlarging mass with or without motor/sensory deficits• Imaging findings are pathognomonic and treated with decompression as surgical excision can cause more nerve damage
Desmoid Tumor• Bland benign fibrous T1 neoplasm• Infiltrative, firm lesions• Can distort tissues, cause pain and have high recurrence rates• Due to fibrous content, Low T2 on T1 AND T2 and enhance• Can have spiculated irregular borders• Treatment with surgery, NSAIDS, radiation• Association Gardner’s syn T1 FS – GI adenomatous polyps, post osteomas, desmoids; AD
Additional History• At time of biopsy, patient recalled stepping on a horseshoe crab when 8 years old. Had to have tail remove from his foot in the emergency room
Foreign Body Pseudotumor (Horseshoe crab tail tip)• Penetrating trauma is common cause of pseudotumors in bone• Often in hands and feet with thorns and wood splinters the most common foreign bodies• Can take a long time to show symptoms• Smooth bony remodeling (as in this case) indicative of a slow indolent process• Often surrounded by fluid or granulation tissue (bright and T2/STIR and enhancement)• Clinical history crucial in making diagnosis!!