The Compression Fracture of Thoracic Spine Due to Methotrexate-Associated Lymphoproliferative Disorder in Rheumatoid Arthritis: A Case Report

Patients with rheumatoid arthritis (RA) are at high risk of developing cardiovascular disease, infections and malignancies during their lifetime, with lymphoma being the most common malignancy. These patients may clinically present with a wide spectrum of lymphoid proliferations or lymphomas, which are called lymphoproliferative disorders (LPD). The prediction sites of LPD can be divided into nodal and extranodal lesions, with the majority being extranodal lesions. The sites of extranodal lesions especially in RA patients with LPD receiving methotrexate (MTX) are the pharynx, liver, spleen, lung, soft tissues, adrenal gland, pleura, bone, kidney, small bowel and breasts. Among these, bone lesions are rare, with the frequency of occurrence in the spine being extremely rare. In this report, we describe a 76-year-old woman with RA suffering from the isolated methotrexate-associated lymphoproliferative disorder (MTX-LPD) in the thoracic spine. This patient complained of unprovoked back pain for two weeks before visiting our hospital. The neoplastic change and the vertebral compression fracture were found at T7, and the pathological examination from needle biopsy of the T7 vertebral body revealed the possibility of diffuse large B-cell lymphoma or MTX-LPD, and no evidence of cancer metastasis. This patient showed clinical improvement after MTX withdrawal and thoracic posterior fusion with spinal instrumentation for T7 compression fracture. At 30 months after MTX withdrawal, the tumoral lesion remained obliterated, and a solid union of T7 was observed.