[Primary pleural of mucosa-associated lymphoid tissue lymphoma].

A 68-year-old female presented with shortness of breath. Chest radiography showed pleural effusion in the right side only. She was suspected of having ovarian cancer because CA125 levels were increased in the pleural effusion, and she consulted our hospital. A chest CT scan showed right pleural nodular lesions. Thoracoscopic pleural resection was performed. Histologic examination of a biopsy specimen showed the diffuse infiltration of small∼medium, mature lymphocytes. These lymphocytes were found to be positive for CD20 and CD79a, but negative for CD3 by immunohistochemistry. These results were interpreted as being consistent with a diagnosis of mucosa-associated lymphoid tissue lymphoma (MALT lymphoma). She commenced chemotherapy with R-CHOP, and the pleural effusion disappeared. MALT lymphoma arising in the pleura is very rare, with only 12 published cases, and most cases have been described in Japan. CA125 levels correlated with the stage, tumor bulk, and presence of effusion. This patient exhibited a high level of CA125 that decreased with therapy.