Multiple myeloma with pleural involvement after pelvic radiotherapy for endometrial carcinoma

Although ionizing radiation is strongest factor linked to multiple myeloma, increased myeloma risk has not been fully explained after pelvic radiation. Pleural involvement of MM is also rare. We present a MM case with pleural involvement as an unusual presentation diagnosed in fifth years of pelvic radiotherapy. A sixty-two-year-old woman with dyspnea and a mass in forehead was admitted to our clinic. Before five year, the patient had received pelvic external beam radiotherapy (RT) with dose of 40 Gy for endometrial adenocarcinoma. PET/CT scan detected FDG uptakes in frontal bone, right pleura, and sacrum. Lambda light chain type multiple myeloma with pleural involvement was diagnosed with histopathological examinations of frontal bone mass, bone marrow, and pleural fluid and with serum/urine electroforesis. The patient died in second course of VAD chemotherapy. Although relation between increased myeloma risk and pelvic radiation is not clear and pleural involvement is rare, multiple myeloma should be included to the differential diagnosis in patients received pelvic radiotherapy or in unexplained pleural effusion.