A total of 16 cases only have been reported in the world specialized literature. This is a new case, of a patient aged 20 years, a male working in the metallurgical industry. This is the first case reported in our country. Clinically the patient presented a painful global swelling of the median third of the clavicula on the left side. Biological constant were normal. Radiographic investigations revealed an increase in volume and a condensation of the median part of the clavicula, and scintigraphical studies revealed an intense incorporation of the radioisotope. Histopathologic studies showed lamellar and spongious bone tissue, with a normal trabecular structure, although considerably thickened. Data for the differential diagnosis are presented, and in the first place those concerning intra-sterno-clavicular hyperostosis, sterno-costo-clavicular arthrosis, chronic subacute osteitis, avascular necrosis of the clavicular epiphysis (Friedrich disease), and Tietze syndrome. The etiopathogenesis of this rare benign clinico-radiologic entity remains unknown.