Abstract
This report presents a case of synchronous primary breast malignant lymphoma and cecal cancer following methotrexate therapy for rheumatoid arthritis. A 76-year-old woman developed rheumatoid arthritis, and methotrexate treatment was started in January 2012. In August 2012, she visited the hospital because of a tumor in the upper outer quadrant of the right breast. A core needle biopsy was performed for the diagnosis of the tumor, which measured 2.8×1.0 cm in size, detected by mammography and ultrasonography. Immunostaining revealed the tumor to be non-Hodgkin's lymphoma (diffuse large B-cell type). Positron emission tomography-computed tomography (PET-CT) showed masses with increased uptake in the right breast and cecum. The cecal mass lesion was diagnosed as a type 2 cecal cancer during colonoscopy, and therefore an ileocecal resection and lymphadenectomy were performed. The pathological findings showed well differentiated adenocarcinoma (3.0×1.7 cm, pT2, ly0, v0, pN0(0/9), pStage II). The Ann Arbor clinical stage was IEA due to a lack of any other abnormal lesions identified by PET-CT or in the bone marrow. Chemoradiation therapy was initiated without surgery.
