A surgical case of methotrexate-associated lymphomatoid granuloma.

We reported a surgical case of methotrexate-associated lymphomatoid granuloma. A 69-year-old female had been treated with methotrexate for rheumatoid arthritis for 35 months. The patient underwent partial resection of the right upper pulmonary lobe for lung cancer when she was 67 years old. A nodule was detected in the left lung field on a chest radiograph performed during the postoperative follow-up period. Computed tomography revealed a 28-mm nodule in the lower left pulmonary lobe. A transbronchial biopsy examination did not lead to a diagnosis. The pulmonary nodule subsequently increased in size. We suspected a malignant tumor and performed lower left lobectomy. A pathological examination revealed lymphomatoid granuloma. Finally, the patient was diagnosed with methotrexate-associated lymphomatoid granuloma based on her history of oral methotrexate treatment.