18F-FDG-PET/CT pulmonary infiltrates in non-Hodgkin's lymphoma patients treated with combined immunochemotherapy: Incidence and clinical characteristics

Background: Pulmonary infiltrates (PIs) detected in patients with non-Hodgkin’s lymphoma (NHL) may present a diagnostic challenge due to their wide differential diagnosis, including infection, pulmonary lymphoma and immunochemotherapy-associated pulmonary toxicity. Objectives: To characterize therapy-associated PIs by positron emission tomography/computed tomography (PET/CT) imaging. Methods: We conducted a historical analysis of¹⁸F-fluorode-oxyglucose positron-emission tomography/computed tomography (¹⁸F-FDG PET/CT) PIs in NHL patients treated with combined immunochemotherapy including rituximab. Incidence of PIs, radiological features, patient characteristics, underlying NHL type, rituximab/chemotherapy dosing schedules, and symptoms were recorded. Therapy-associated PIs were defined as new or worsening PIs appearing after treatment onset, without evidence of active pulmonary lymphoma or infection. Results: Among 80 patients who met the pre-specified criteria, therapy-associated PIs were identified in 17 (21%), 6 of whom had accompanying symptoms. Increased FDG uptake was observed in nine, and PI resolution in six. The incidence of PIs was higher in females and in patients with aggressive lymphoma who were at advanced stages and who had received treatment consisting of a combination of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone every 14 days (R-CHOP-14). Conclusions: This characterization of therapy-associated PIs may support the clinician managing NHL patients. Further prospective studies are needed to establish the role of each therapeutic component and the natural history of this phenomenon.