Methotrexate-associated lymphoproliferative disorder affecting the gingiva and intestinal mucosa with intestinal perforation: A case report

According to the fourth revised edition of the world health organization classification of hematopoietic tumors, methotrexate (MTX)-associated lymphoproliferative disorder (MTX-LPD), an atypical pathological condition, is categorized under other iatrogenic immunodeficiency-associated lymphoproliferative disorders (OIIA-LPDs). An 80-year-old woman presented with OIIA-LPDs that simultaneously occurred in the gingiva and intestinal mucosa, causing intestinal perforation requiring emergency surgery. She was referred to our hospital because of poor wound healing after maxillary right first molar extraction. She had been prescribed MTX and prednisolone for rheumatoid arthritis and bisphosphonate for osteoporosis. We diagnosed her with medication-related osteonecrosis of the jaw, as the lesion showed bone exposure with mild redness and swelling of the surrounding gingiva and a cytological result of Class II. However, 9 months later, following the exfoliation of a partial sequestrum of the maxillary right first molar, a rapidly growing mass with gingival necrosis appeared, necessitating a biopsy. Simultaneously, abdominal pain worsened, and computed tomography revealed intestinal perforation; an emergency laparotomy was performed to remove the perforation and the surrounding ulcer-prone area. Histopathological examination of both lesions revealed diffuse large B-cell lymphomas. The final diagnosis was of MTX-LPD, as the mass, gingival necrosis, and residual small intestinal ulcer disappeared 2 months after MTX discontinuation. The exposed bone completely disappeared after 24 months, and no recurrence was noted after 60 months following MTX discontinuation. Although intestinal perforation due to MTX-LPD is extremely rare, patients with RA are immunosuppressed. Therefore, MTX-LPD must be recognized as a dangerous condition that requires careful general monitoring in such patients.