Side effects of rituximab are mild in most cases, but there have been a few cases of severe pulmonary toxicity reported in elderly patients. Here we report a case of interstitial pneumonitis following rituximab treatment in a young patient. A 35-year-old woman with diffuse large B-cell lymphoma was admitted complaining of dry cough and dyspnea without fever after the 3 treatments with rituximab-CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone) chemotherapy. Her chest CT with high- resolution CT scanning confirmed the presence of bilateral diffuse ground-glass opacities. The analysis of arterial blood gases indicated hypoxemia. The pulmonary function testing showed a restrictive pattern. There were no other findings suggesting an infection. The findings were compatible with a rituximab-induced interstitial pneumonitis. After the patient was treated with prednisolone, the symptoms resolved. Cases with rituximab-induced interstitial pneumonitis develop principally in elderly patients. However, the condition also can occur in young patients.

Keywords: Rituximab, Interstitial pneumonitis, Young patient, Diffuse large B-cell lymphoma