Kidney biopsies in methotrexate-treated psoriatics.

Kidney biopsies were studied in 19 psoriatics treated with methotrexate (MTX) from 1 month to 16 years. Only 3 of the patients had received the drug for less than 1 year. Four patients had been treated for more than 10 years. The total doses of MTX ranged from 30 to 14,340 mg. In 17 of the 19 patients the cumulative MTX dose was 500 mg or more. In 9 patients the cumulative doses were over 2 g. With the exception of 1 patient, which presented sequelae of acute renal failure unassociated with MTX treatment, all other biopsies showed renal structures which, assessed by routine judgement, were found normal. Semiquantitative evaluation of interstitial fibrosis and arteriolar hyalinosis as well as interstitial volume estimated by morphometry showed no significant changes. No patient showed clinical or laboratory signs of renal impairment.