Two Cases of Interstitial Pneumonitis Caused by Rituximab Therapy
A previously healthy 73-year-old man visited our hospital because of a left cervical mass. Incisional biopsy of the cervical node revealed a diffuse large B-cell lymphoma stage IIIA. The patient received seven cycles of R-CEOP combination chemotherapy (rituximab 375 mg/m2, cyclophosphamide 750 mg/ m2, epirubicin 50 mg/m2 and vincristine 2 mg IV on D1 and prednisolone 100 mg PO on D1-5). The response was partial after the 6th cycle. After the 3rd cycle of R-CEOP, he complained of cough and purulent sputum. A chest computed tomography revealed sub segmental consolidation with peripheral ground glass opacity (GGO) in left upper lobe of the lung. After the administration of parenteral antibiotics, symptomatic improvement and disappearance of the infiltration on X-ray were observed. After an additional four cycles of chemotherapy, he complained of cough, sputum and exertional dyspnea, NYHA class II. Auscultation revealed end-expiratory Velcro-like rales at both lower lung fields. Arterial blood gas analysis was PH; 7.49, PaCO2; 29.2 mmHg, PaO2; 74.3 mmHg, and HCO3; 22.5 mmol/L. The cultures of blood and sputum were all negative for bacteria, tuberculosis and fungi. Chest computed tomography showed a markedly increase in the extent of sub pleural GGO at both lungs (). Pulmonary function testing showed a mild restrictive pattern with FEV1; 2.19 L/min (87% of normal predicted value), FVC; 2.60 L/min (68% of normal predicted value), FEV1/FVC; 84%, and DLCO; 10.3 mL/mmHg/min (59% of normal predicted value). A bronchoalveolar lavage sample showed a lympho-dominant nature with a CD4/CD8 ratio of 1.5. After the diagnosis of interstitial pneumonitis, methylprednisolone 60 mg qd was administered for five days. Symptomatic improvements were followed by a change of dose to prednisolone 20 mg once daily. After five weeks of steroid therapy, pulmonary function testing showed an objective response with FEV1; 1.90 L/min (71% of normal predicted value), FVC; 2.57 L/min (63% of normal predicted value), FEV1/FVC; 74%, and DLCO; 13.4 mL/mmHg/ min (74% normal predicted value).