A Case of Immunodeficiency-associated Lymphoproliferative Disease Requiring Differentiation from Postoperative Lung Metastasis of Lung Cancer

Abstract

The patient was a 76-year-old man. He underwent right upper lobectomy 13 years and segmentectomy of the left upper major division 5 years previously for lung adenocarcinoma and was taking methotrexate (MTX) and anticoagulants for rheumatoid arthritis and deep vein thrombosis. He had been followed up for lung masses that were enlarging and shrinking for 4 months after lung surgery and was referred to our department due to wobbliness and hypercoagulability. Blood tests showed high Ca level and marked prolongation of coagulability, and a computed tomography (CT) showed enlarged lung masses and multiple liver masses, which led us to suspect recurrence. After emergency hospitalization and improvement of coagulability, a biopsy was performed by upper esophagogastroduodenoscopy on a depressed lesion in the duodenum, and a pulmonary needle biopsy was also performed on the lung lesion. Immunostaining of the pathology showed strong positivity in diffusely proliferated lymphocytes for both LCA and L26 in the lung and duodenum biopsy specimens, and high levels of soluble IL-2 receptors in the blood, leading to the diagnosis of diffuse large B-cell lymphoma (DLBCL), which developed in an iatrogenic immunodeficient state while taking MTX for a long time. Immunodeficiency-associated lymphoproliferative disease should also be differentiated in RA patients receiving MTX, when multiple lung masses appear, suggesting recurrence after lung cancer surgery.