Acute onset pyothorax-associated lymphoma (PAL) with inflammatory features.

Pyothorax-associated lymphoma (PAL) is a B-cell non-Hodgkin's lymphoma, and develops after 20-40 years of pyothorax or pleuritis including tuberculosis. An 88-year-old Japanese woman developed fever and right pleural effusion. No mycobacterium was recognized by Ziel-Neelsen stain, culture tests and PCR technique in the effusion. The patient was diagnosed as non-specific pleuritis. No tumor formations were seen in the right pleura by imaging modalities, and she was treated by antibiotics. Eight months later, she complained of severe back pain and fever. Imaging modalities revealed many tumors in the right pleura, and biopsy of the tumors was performed. The biopsy showed severe diffuse proliferation of lymphoid cells. The lymphoid cells consisted of atypical large lymphoid cells and small lymphoid cells. The large atypical cells were positive for CD45 and CD20 but negative for CD15 and CD30, thus confirming B cell neoplasm. Ki-67 labeling was 79%. The small cells were positive for CD45, CD20 and CD3, reflecting a mixture of mature B and T-cells. The small cells appeared non-neoplastic inflammatory cells. CD68-positive macrophages were also scattered. In situ hybridization for EB virus DNA showed positive signals in the large atypical B-cells and, to a lesser degree, in the small lymphocytes. The author thinks that this tumor is PAL with inflammatory reaction. The present case shows that the duration between PAL and pleuritis can be very short, and PAL may be associated with inflammatory reaction at the early neoplastic stage.