Diffuse large B‐cell lymphoma in a patient with dermatomyositis‐associated interstitial lung disease: A case report

A 63‐year‐old man presented to our clinic complaining of cough and exertional dyspnea. He was diagnosed with dermatomyositis‐associated interstitial lung disease (DM‐ILD) with typical rashes, an elevated creatine kinase level and chest high‐resolution computed tomography (CT) manifestations. His symptoms and lung shadows improved after treatment with corticosteroids, immunosuppressants and pirfenidone, although his serum creatine kinase level remained elevated. An expanding nodule in the lower left lung and lymphadenopathy in the right cardiophrenic angle were visible on the repeated chest CT scan during follow‐up approximately one year later. Empirical antibiotics had no effect. A positron emission tomography‐computed tomography (PET‐CT) scan showed an increased standard uptake value (SUV) in the newly emerged pulmonary nodule, mediastinal lymphadenopathy and multiple hepatic masses. He was diagnosed with diffuse large B‐cell lymphoma following liver biopsy. After eight cycles of rituximab‐cyclophosphamide, doxorubicin, vincristine, and prednisone (R‐CHOP) chemotherapy, the lymphoma was cured clinically, and his interstitial lung disease (ILD) had improved. Tumor surveillance should be performed during DM‐ILD follow‐up, and rituximab could be a promising choice for DM‐ILD concurrent with lymphoma.