We report a case of a patient of 58 years old who suffered from a left apical opacity occurring in a context of deterioration in general health. Subsequent clinical developments were dominated by the ophthalmic disease and a frontal syndrome. The radiological work-up showed tumoral lesions which had developed from the first rib, from the structures at the base of the cranium and the frontal area and were associated with multiple lacunae of the cranial vault. There was evidence of hyperproteinaemia, and an IgG gamma monoclonal gammopathy, a significant medullary plasmocytosis with morphological anomalies of the plasmocytes leading to a diagnosis of myeloma with a plasmocytoma of the rib and the retro-orbital area. Thoracic disease associated with this pathology is common but mainly present as osteolytic lesions. The occurrence of intrathoracic plasma cell tumours is rarer as are orbital manifestations. In spite of treatment which can frequently lead to an objective response, the prognosis of this disorder remains gloomy.