[A rare localization of solitary plasmocytoma]

Solitary bone plasmocytoma is rare, characterized by malignant plasmocyte proliferation, derived from a sole B lymphocyte clone located on a bony segment without medullar invasion. It, above all, affects the thoracolumbar spine. Costal involvement is rarely described.

The authors report the case of a 60-year-old man who complained of dyspnea, dry cough, and thoracic pain four months before admission. Thoracic imaging revealed a left apical tissue mass with osteolysis of the first rib. A transparietal biopsy of the mass was not helpful. Surgical biopsy concluded as to the diagnosis of costal plasmocytoma. All of the examinations carried out to search for other localizations were negative confirming the solitary nature of the tumor. The treatment consisted of complementary radiotherapy at a dose of 45Gy. The patient was in remission after eight months.

Solitary costal plasmocytoma should be called to mind when confronted with a lytic tumor of the rib. The treatment is based on surgery and radiotherapy. The prognosis is dominated by the risk of progression to multiple myeloma.