Foreign body granuloma mimicking recurrence of malignant pleural mesothelioma.

A 72-year-old man visited our hospital due to right pleural effusion. He had worked as a welder at a shipbuilding company and had been exposed to asbestos. Cytological examination and thoracoscopic pleural biopsy yielded a diagnosis of epithelial malignant pleural mesothelioma (MPM); extrapleural pneumonectomy (EPP) was performed. Two years later, he became aware of right-back swelling that became a fist-sized mass over 2 months. Microscopy of a tissue specimen revealed no malignant cells, but did indicate foreign body granuloma. Subcutaneous lesions that develop after EPP do not necessarily result from the recurrence of MPM, but could have benign etiologies.