We describe the development of a cutaneous lymphoproliferative disorder in a patient with rheumatoid arthritis who was treated with methotrexate. Skin manifestations were characterized by thrombophlebitis-like lesions and ulcerated nodules. Histologic examination revealed large polymorphic atypical cells including Reed-Sternberg–like cells expressing CD20 and CD30 in the dermis and subcutaneous tissues. Tumor cells infiltrated the walls of dermal arterioles, subcutaneous arteries, and veins, leading to the destruction of vascular structures. Activation of Epstein-Barr virus was detected. Skin lesions improved remarkably after the discontinuation of methotrexate. This case illustrates the rare occurrence of cutaneous vascular involvement in methotrexate-related lymphoproliferative disorder that did not require any specific chemotherapy.