[A case of plasmacytoma of the ribs with intrathoracic tumors].

A 75-year-old male was admitted because of two tumors, one in the left middle lung field and one in the right upper lung field. Chest CT revealed intrathoracic tumors extending from destroyed ribs. Biopsy specimens of both tumors showed well-differentiated plasmacytoma. Retrospective investigation suggested that solitary plasmacytoma of bone (SPB) originating in the left fourth rib had developed into multiple myeloma (MM). Both tumors were treated with doses of 50 Gy irradiation and responded very well. Intrathoracic plasmacytomas have rarely been observed, so we have no established classification or therapy. According to reported cases, we classified intrathoracic plasmacytomas into 5 groups, and consider that treatment with doses of over 40 Gy irradiation was adequate for local control.