Acute methotrexate poisoning with diffuse rash: a case report

Methotrexate is an anti-metabolite drug and one of the folic acid analog that it can play an important and functional role in the treatment of many malignancies and inflammatory diseases. However, the development of petechiae (maculopapular rash) is a very rare complication.

The patient was a 77 years old woman, Aryan race, who was known a case of severe and progressive rheumatoid arthritis. She previously was treated by multiple drugs such as salicylates, gold, corticosteroids, because of unresponsiveness to these drugs, physician prescribed methotrexate once a day, but patient misunderstands and use three times per day for days. Patient with this history referred to a poisoning emergency. In a physical exam, she had oral and throat erythema and swelling of mucosa. In the funduscopy of eyes, bottom of the eyes was normal and conjunctival eyes were prurient she had multiple petechiae at the upper part of chest and base of neck and shoulders and arms with no swelling around petechiae. The lesion had no itching. She had no other sign besides laboratory analysis showed a high level of creatinine, leukopenia, decreased the level of platelets, patient with high suspicious of methotrexate poisoning underwent to granulocyte-macrophage colony-stimulating factor (GM-CSF) and folic acid treatment. After treatment all of her signs recovered and laboratory tests became normal.

At the time of taking methotrexate by the patient, even with appointment of a specialist physician, with any skin signs such as maculopapular rash without itching, we should consider poisoning with methotrexate, and think appropriately about it. This suggests that methotrexate can cause side effects even at low doses.