A Case of Femoral Artery Aneurysm Caused by Methotrexate Associated Lymphoproliferative Disease.

An 82-year-old man with left leg edema was referred to our department after an ultrasound examination by his previous physician, which revealed deep vein thrombosis (DVT) in the left superficial femoral vein and a left common femoral artery aneurysm (CFAA). The DVT was caused by the CFAA. The patient was adjudged to be at high risk of peripheral embolization due to the irregular shape of the varicose vein and a large amount of mural thrombus. Surgery was performed to replace the artificial blood vessel. The patient displayed firm adhesion to the surrounding area, marked lymph node swelling, and a large amount of mural thrombus in the mass. The superficial femoral artery (SFA) demonstrated severe intimal thickening and partial dissection. The postoperative course was good, and the patient was undergoing rehabilitation to be discharged home; however, B-cell lymphoma was suspected based on the pathology results of the mass wall submitted intraoperatively. The patient had a history of rheumatoid arthritis and was treated with methotrexate (MTX). During the course of his illness, a subcutaneous mass was found on his right forearm, and a skin biopsy revealed MTX-associated lymphoproliferative disease (MTX-LPD), which had resolved with MTX withdrawal. The histopathological results of the skin biopsy matched those of the CFAA mural thrombus, and Epstein-Barr virus-positive cells were also observed, leading to the diagnosis of MTX-LPD, which was considered to be the cause of CFAA. No MTX-LPD was identified in the vessel walls or intramural thrombus. We herein report a case of CFAA with an extremely rare etiology and clinical presentation.