Low-grade B-cell lymphoma of mucosa-associated lymphoid tissue in the lung: a report of a case with pleural dissemination.

A 79-year-old man with an abnormal shadow on a chest radiograph was referred to our hospital for further examination. Open lung biopsy revealed numerous nodules on visceral pleura and the tumor, obtained by wedge resection of the left upper lobe of the lung, consisted of centrocyte-like cells and lymphoplasmacytoid cells, expressing CD20 and CD79a. These cells invaded bronchiolar epithelium to form lymphoepithelial lesions. The pleural-based nodules were similarly composed of the same cells as those in the left upper lobe tumor. To our knowledge, pleural dissemination of low grade B-cell lymphoma of mucosa-associated lymphoid tissue has not been reported previously.