Hypertrophic osteitis of the medial end of the clavicle.

A 9-year-old boy had a spontaneous onset of enlargement of the medial end of the clavicle due to extensive sclerosis and periosteal reaction. There was no clinical or laboratory evidence of infection. Biopsy revealed an inflammatory exudate, and histochemical staining for Langerhans'-cell histiocytosis was negative. Hypertrophic sclerosis causing painful enlargement of the medial end of the clavicle in isolation should be distinguished from condensing osteitis and chronic recurrent multifocal osteomyelitis. An early biopsy to exclude neoplasia is recommended.