Methotrexate toxicity presenting as ulceration of psoriatic plaques: a report of two cases.

We describe two cases of methotrexate toxicity occurring due to inappropriate self-medication with the drug. The first patient was a 57-year-old man with plaque-type psoriasis on intermittent methotrexate therapy. He discontinued his medications for 2 months and had exacerbation of psoriasis for which he self-medicated with methotrexate following which he developed ulceration of the psoriatic plaques accompanied by bone marrow suppression. The second patient was a 68-year-old man with chronic plaque-type psoriasis for 20 years and was being treated with intermittent methotrexate for 15 years. He also self medicated with oral methotrexate 15 mg daily for 7 days for exacerbation of psoriasis and developed ulceration of the psoriatic plaques with bone marrow suppression and evidence of gastrointestinal erosions.