Pleural Mucosa-associated Lymphoid Tissue Lymphoma with Trisomy 18.

A 39-year-old man was referred to our hospital due to a chest radiograph abnormality. Fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography revealed a hypermetabolic pleural mass in the right upper hemithorax without pleural effusion and small infiltrates in the right lower and left upper lobe of the lung without any uptake of fluorodeoxyglucose (Picture 1). Immunohistochemical studies of the pleural biopsy specimens showed diffuse infiltration of lymphocytes expressing CD20, CD79a, and Bcl-2. A fluorescence in situ hybridization assay using the probe of API2-MALT1 detected three MALT1 signals, suggesting trisomy 18 (Picture 2). Immunohistochemical studies of the pulmonary biopsy specimens showed nodular lymphoid hyperplasia. A bone marrow biopsy did not show any lymphoma involvement. These findings suggested pleural-based mucosa-associated lymphoid tissue (MALT) lymphoma. This was a unique case of pleural MALT lymphoma without pleural effusion and with trisomy 18 (1). Trisomy 18 leads to the overexpression of MALT1 and activation of NF-κB, contributing to the oncogenesis of pleural MALT lymphoma (2).

Picture 1.

Picture 2.

The authors state that they have no Conflict of Interest (COI).