The management of pyothorax-associated lymphoma using 18F-FDG PET/CT

Objective Pyothorax-associated lymphoma (PAL) is a rare form of lymphoma and its management on 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET) combined computed tomography (CT) has not been well reported. The purpose of this study was to evaluate the usefulness of FDG PET/CT in patients with PAL. Materials and methods Twenty-four PET/CT images in seven patients (5 men and 2 women) with PAL were studied retrospectively. Five of the 24 PET/CT scans were done for diagnosis and staging, 6 for restaging, 3 for follow-up, and 10 to evaluate the treatment response. PET/CT scan interpretations were performed visually and using the maximum standardized uptake values (SUVmax). Additionally, the efficacy of the enhanced CT findings in pre- and post-treatments was described. Results Six of the 7 patients with PAL received radiotherapy, and the efficacy of treatment was observed in their lesions. The percentage decrease of SUVmax in PAL was useful in providing complementary information. Enhanced CT findings showed decreasing enhancement of PAL after treatment; however, in five cases, residual masses were confirmed after treatment. Conclusion FDG PET/CT may be an ideal modality for reducing the false-positive interpretation of residual masses occurring after treatment for PAL. The SUVmax provides complementary information for the management of PAL.