Severe Pancytopenia Following Single Dose Methotrexate In Psoriasis: A Rare And Potentially Lethal Manifestation

Area of Science:

• Dermatology
• Pharmacology
• Hematology

Background:

• Methotrexate is a key anti-metabolite chemotherapy agent widely used for treating severe chronic plaque psoriasis.
• Psoriatic plaque erosion is an uncommon, yet serious, toxicological manifestation associated with methotrexate therapy.
• This erosion is recognized as a potential indicator of impending bone marrow suppression, specifically pancytopenia.

Observation:

• A 48-year-old male patient with a history of chronic plaque psoriasis presented with a 5-day history of extensive oral and genital erosions.
• The patient also exhibited fissuring of the palms and soles, consistent with a severe dermatological reaction.
• He had recently received a single 15 mg dose of methotrexate for his psoriasis.

Findings:

• Laboratory investigations confirmed severe pancytopenia (a significant reduction in all blood cell types) and nephropathy in the patient.
• The clinical presentation and laboratory findings strongly correlated with methotrexate toxicity.
• Treatment necessitated supportive care including folate antagonists, granulocyte colony-stimulating factor (G-CSF), fluid resuscitation, and blood/platelet transfusions.

Implications:

• This case underscores the critical importance of recognizing psoriatic plaque erosion as a warning sign for methotrexate-induced pancytopenia.
• Prompt identification and management, including supportive therapies, are crucial for patient recovery from severe methotrexate toxicity.
• Clinicians should maintain a high index of suspicion for methotrexate side effects in patients presenting with mucocutaneous lesions and hematological abnormalities.