Early-onset pancytopenia and skin ulcer following low-dose methotrexate therapy

Pancytopenia is a rare but serious adverse effect of low-dose methotrexate (MTX) sodium therapy, and this case report describes a very early-onset of pancytopenia and cutaneous lesions after three days of ingestion. A 64-year-old man was presented to Emergency Department with weakness, fever, poor appetite, nausea, and vomiting after he had had accidentally ingested MTX tablets (2.5 mg) twice a day for the last three days. On initial examination, several painful lesions in his oral mucosa and a cutaneous ulceration on his right foot were also observed. He had severe pancytopenia, poor kidney functions, and abnormal coagulation parameters. The blood level of MTX was found to be within therapeutic range. He was treated with leucovorine, intravenous antibiotics, and appropriate blood transfusions; he was discharged from hospital without any sequela. Pancytopenia associated with low-dose (cumulative dose of 15 mg in 3 days) MTX therapy had not been reported previously. The Naranjo probability scale showed pancytopenia and skin ulcer associated with low-dose MTX therapy as probable adverse reactions. Risk factors for pancytopenia such as renal insufficiency, hypoalbuminemia, low folate levels, concomitant infections, concomitant use of drugs, and folate supplementation were not identified in our patient. Although pancytopenia associated with low-dose MTX therapy is not expected as early as 3 days after initiation of the therapy, physicians should also be aware of this life threatening adverse effect during the very first days of MTX therapy for rheumatoid arthritis patients.