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Methotrexate is an antimetabolite anticancer drug frequently used in the treatment of extensive chronic plaque
psoriasis. Psoriatic plaque erosion is a rare toxic side effect of single-dose methotrexate and is described as a sign of the
impending pancytopenia. Here, we report a case of a 48-year-old male, presented with multiple oral and genital erosions,
fissuring over palm and soles for 5 days. His laboratory tests revealed severe pancytopenia and nephropathy. He had a
history of chronic plaque psoriasis for which he took a single dose of 15 mg methotrexate. During the hospital stay, the
patient needed folate antagonist, granulocyte colony stimulating factor (G-CSF), intravenous fluids, blood transfusions,
and platelet transfusions. He recovered within 12 days of admission.
Rationale, objectives and design of PURE, a prospective registry of patients with moderate to severe chronic plaque psoriasis in Canada and Latin America