76 AJR:194, January 2010 patients (92%) with pyothorax-associated lymphoma had a history of artificial pneu- mothorax therapy. Narimatsu et al. [4] re- ported that 78 of 98 patients (80%) had a similar history. According to the literature, the mean age at diagnosis of pyothorax-associated lymphoma is approximately 60 years, and there is a predi- lection for men [1–4]. Common symptoms in- clude chest pain, fever, and a palpable chest wall mass, which occur in approximately one half of patients. Respiratory symptoms such as productive cough, hemoptysis, and dyspnea are found in one fourth of patients [1, 2, 4]. Aozasa [5] reported a 2% incidence of pyotho- rax-associated lymphoma among patients with concomitant chronic empyema. The current pathophysiologic understanding of the dis- ease suggests that both chronic Epstein-Barr virus (EBV) infection and an immunocom- Pyothorax-Associated Lymphoma: Imaging Findings Takuya Ueda 1 Christe Andreas 1 Jun Itami 2 Kunihisa Miyakawa 3 Hajime Fujimoto 4 Hisao Ito 5 Justus E. Roos 1 Ueda T, Andreas C, Itami J, et al. 1 Department of Radiology, Stanford University School of Medicine, 300 Pasteur Dr., Rm. S-072, Stanford, CA 94305. Address correspondence to T. Ueda (takueda-rad@umin.ac.jp). 2 National Cancer Center Hospital, Tokyo, Japan. 3 Nagano PET and Diagnostic Center, Nagano, Japan. 4 Department of Radiology, Numazu City Hospital, Shizuoka, Japan. 5 Department of Radiology, Graduate School of Medicine, Chiba University, Japan. Cardiopulmonary฀Imaging฀•฀Original฀Research AJR 2010; 194:76–84 0361–803X/10/1941–76 © American Roentgen Ray Society P yothorax-associated lymphoma is a rare type of lymphoma that typically occurs in patients who have undergone artificial pneu- mothorax therapy for tuberculosis [1–4]. Re- sults of several studies [1–4] have suggested that the development of pyothorax-associat- ed lymphoma is triggered by long-standing empyema, that is, lasting for more than 20 years after the initial pneumothorax treat- ment. Until approximately 1970, artificial pneumothorax therapy for tuberculosis was performed mainly on younger patients. This treatment was gradually replaced by clini- cally more effective chemotherapy. A long latency period between the artificial pneu- mothorax treatment and the development of pyothorax-associated lymphoma, sometimes more than 40 years, has been reported [1–4]. Nakatsuka et al. [2] reported that 98 of 106 Keywords: CT, empyema, pleura, pyothorax-associated lymphoma, tumors DOI:10.2214/AJR.09.2603 Received February 19, 2009; accepted after revision July 12, 2009. OBJECTIVE. The purpose of this study was to evaluate the radiologic features of pyotho- rax-associated lymphoma on CT scans and chest radiographs. MATERIALS฀AND฀METHODS. Radiographs and CT scans of 21 patients with bi- opsy-proven pyothorax-associated lymphoma (17 men, four women; median age, 71 years; range 52–77 years) were retrospectively identified. Two readers in consensus analyzed the morphologic imaging features of pyothorax-associated lymphoma and determined their re- lation to the preexisting chronic empyema cavity. In 13 cases, gallium scans were available and were reviewed. RESULTS. Sixteen patients had a history of artificial pneumothorax therapy for tubercu- losis. Pyothorax-associated lymphoma was visualized mainly (71.4% of cases) as extrapul- monary pleural masses on chest radiographs. The CT features included a lenticular (60%) or crescentic (20%) soft-tissue mass located eccentrically at the margin of a coexistent empy- ema cavity, which was present in all cases. Masses of pyothorax-associated lymphoma were commonly located in the lateral costal pleura (50%) or at the costophrenic angle (30%). The tumor matrix often appeared heterogeneous and contained areas of necrosis (60%). Direct in- vasion of the chest wall, ribs, lung parenchyma, and abdomen was found in 75%, 50%, 25%, and 25% of patients. Gallium scans, when available, showed marked uptake in 10 of 13 pa- tients (76.9%). CONCLUSION. In patients who have undergone artificial pneumothorax therapy for tu- berculosis more than 20 years in the past, a pleural soft-tissue mass adjacent to the margin of a coexistent empyema cavity suggests the presence of pyothorax-associated lymphoma. Knowl- edge of the typical radiologic findings and locations of pyothorax-associated lymphoma help in the diagnosis of this rare pathologic entity. Ueda et al. Pyothorax-Associated Lymphoma Cardiopulmonary Imaging Original Research Downloaded from www.ajronline.org by 52.73.204.196 on 05/18/22 from IP address 52.73.204.196. Copyright ARRS. For personal use only; all rights reserved