Methotrexate-induced panniculitis in a patient with rheumatoid arthritis

Area of Science:

• Rheumatology
• Dermatology
• Pharmacology

Background:

• Methotrexate is a common disease-modifying antirheumatic drug (DMARD) used for rheumatoid arthritis (RA).
• Methotrexate-induced accelerated nodulosis (MIAN) is a recognized adverse effect of methotrexate therapy.
• Panniculitis is an uncommon pathological finding in MIAN.

Observation:

• A 31-year-old female with seropositive RA on methotrexate presented with painful subcutaneous nodules on her forearms.
• Clinical and histological examination confirmed panniculitis.
• This presentation differed from typical MIAN, which usually involves classic rheumatoid nodules.

Findings:

• The patient was diagnosed with methotrexate-induced panniculitis.
• Review of MIAN literature indicates panniculitis is rarely reported as a pathological finding.
• This case underscores the variability in MIAN presentations.

Implications:

• Recognizing methotrexate-induced panniculitis is crucial for accurate diagnosis in RA patients on methotrexate.
• It expands the differential diagnosis for accelerated nodulosis.
• The optimal management, including methotrexate discontinuation, requires further investigation.