舌潰瘍を契機に診断されたMTX関連リンパ増殖性疾患の1例

抄録

Methotrexate (MTX) has been widely used to treat rheumatoid arthritis. Recently, however, several studies have suggested an increased risk of malignant lymphoma in patients treated with MTX. We report such a case of MTX-associated lymphoproliferative disorder (MTX-LPD) that was diagnosed on detection of ulceration of the tongue. A 70-year-old woman was referred to our clinic because of severe pain with associated a unilateral ulcer on the left side of the tongue. The lesion appeared similar to a giant aphtha, but was not surrounded by induration. Microscopic examination of a biopsy specimen demonstrated a lymphocytic infiltrate with increasingly atypical histopathological features. The atypical cells were positive for CD20, EBER-ISH, and LMP-1. The patient had a history of rheumatoid arthritis diagnosed 14 years previously, and administration of low-dose MTX (8 mg/weekly) had been started 17 months before presentation. Based on the medical history and results of histopathological examination, a final diagnosis of MTX-LPD was made. The lesion responded well to the withdrawal of MTX, followed by chemotherapy (R-CHOP). There have been no signs of recurrence for 23 months since the withdrawal of MTX. Because of the increased risk of lymphoid malignancy, oral lesions should be carefully observed in patients with rheumatoid arthritis who receive low-dose MTX.