A mass originating from chronic pyothorax in the pleural cavity

Abstract

A 71-year-old male with a past history of tuberculous pleuritis was referred to our hospital in 2008 because of right chest pain. Chest computed tomography (CT) demonstrated a huge mass originated from chronic pyothorax in the right pleural cavity, invading the chest wall. 2-[F]fluoro-2-deoxy-D-glucose Positron Emission Tomography (FDG-PET) imaging showed strong uptake only in the tumor of the right chest wall (Image 1A). Immunohistochemical staining and Southern blot hybridization of biopsied specimens revealed that the diagnosis was CD20 negative pyothorax-associated diffuse large B cell lymphoma. In situ hybridization for Epstein-Barr virus (EBV) disclosed EBV-encoded small RNA expression in the lymphoma cells. Clinical stage was IE, and international prognostic index was low intermediate. First, three courses of pirarubicin-cyclophosphamide, vincristine, prednisolone (COP) were administered. Then confirming that FDG-PET became negative (Image 1B), involved-field radiotherapy of 50 Gy was added. No sign of relapse has been found for more than 2 years. Pyothorax-associated lymphoma (PAL) is defined as nonHodgkin’s lymphoma of exclusively B-cell phenotype developing in the pleural cavity of patients with chronic pyothorax [1,2]. Most of PAL cases express CD20; however, there are a small proportion of cases which do not express B cell antigens such as CD20 and CD79a [3,4]. It is suggested that PAL is strongly associated with EBV [5,6]. A mass in the pleural cavity with a history of tuberculosis should cause one to consider PAL in the differential diagnosis.