Liver biopsy in psoriatic arthritis to detect methotrexate hepatotoxicity

The use of methotrexate in the treatment of psoriatic arthritis is associated with risk of hepatotoxicity. However, monitoring of liver-associated enzymes often lacks sensitivity, and guidelines for serial liver biopsies in psoriatic arthritis are not yet well established. We performed a retrospective review of all patients with psoriatic arthritis receiving methotrexate who were enrolled in the disease-modifying anti-rheumatic drug clinics (DMARD clinics) at the Air Force and Army hospitals in San Antonio, Texas. Information was obtained regarding methotrexate regimen, liver-associated enzyme results, and liver biopsy results. Thirty psoriatic arthritis patients were taking methotrexate in the DMARD clinics. Seventeen patients had a total of 21 biopsies. Biopsies were performed for surveillance dictated by cumulative dose. Liver biopsies were graded on Roenigk scale of I-IV where I is mild steatosis, IT is moderate steatosis, Ma is mild fibrosis, IIIb is severe fibrosis, and IV is cirrhosis. Ten biopsies were grade I, 5 were grade II, 5 were grade IIIa, I was grade IIIb, and none were grade IV. In this very small retrospective study, regular monitoring of liver-associated enzymes did not correlate with histologic deterioration in our patients. Until prospective studies are performed, we suggest that routine liver biopsies are necessary to monitor for methotrexate hepatotoxicity in psoriatic arthritis.