Methotrexate Induced Allergic Stomatitis Tending towards Erythema Multiforme

OBJECTIVE: To highlight the diagnostic procedures and treatment intervention to control methotrexate induced allergic stomatitis.

METHOD: A case of a 60-year old man suffering from rheumatoid arthritis that was placed on a daily dose of 5mg methotrexate for two weeks by an orthopaedic surgeon, at the Orthopaedic Unit, University of Benin Teaching Hospital.

RESULT: Patient presented at the dental clinic of the hospital, with painful ulceration of the vermilion border of the upper and lower lips, covered with pseudomembranous necrotic tissue and marked halitosis. An initial diagnosis of methotrexate induced allergic stomatitis was made. After a few days, the patient came down with crusted and haemorrhagic ulceration, as well as erythematous patches on the lips. There were also bilateral bullous eruptions of the upper and lower extremities, with associated complaints of weakness, fever and occasional seizure attacks. Oral swab for microscopy, culture and sensitivity (M/C/S) revealed that there was a secondary infection by staphylococcus aureus. A definitive diagnosis of erythema multiforme complicating methotrexate induced allergic stomatitis was made. Withdrawal of the drug and the use of alternative medication were suggested to the orthopaedic surgeon, which was promptly adhered to. We also placed the patient on promethazine (antihistamine), Ciprofloxacin and warm saline mouth rinse. There was complete resolution of the skin and mucosal lesions after 12 days of initial presentation.

CONCLUSION: Methotrexate induced allergic stomatitis is a rare adverse effect of the drug. However, clinicians especially dental surgeons, should be observant, to ensure early diagnosis and treatment of this condition before it develops into a multi-system lesion.

Key words: Methotrexate, Allergic stomatitis, Erythema multiforme