it is one of the most commonly used medicines in the treatment of rheumatoid arthritis or psoriatic arthritis . we report the case of an adult woman with psoriatic arthritis who developed acute severe hepatitis following long - term treatment with mtx . the periodic biological monitoring of liver enzymes : alanine aminotransferase ( alat ) , aspartate aminotransferase ( asat ) , gamma - glutamyl transpeptidase ( gamma - gt ) performed every 6 months did not reveal any abnormalities . mtx was stopped in the year 2005 due to remission of the disease . in 2009 , it was reintroduced at a dose of 15 mg / week due to decompensation of the disease . monitoring of liver enzymes performed every 6 months showed an elevation < 2 times the normal levels on average of asat and alat since 2010 . assessing the risk - benefit ratio and given the severe decompensation of the disease , mtx was continued . in may 2013 , patient presented with jaundice following the development of asthenia and weight loss . laboratory investigation showed the following results : prothrombin time ( 71% ) , asat 580 u / l , alat 620 u / l , serum gamma - gt 146 iu / l , serum alkaline phosphatase 170 iu / l and total serum bilirubin 12 mg / dl . antimitochondrial antibodies ( titer > 1/40 ) and antinuclear antibodies ( titer of 1/640 ) were detected in serum . routine laboratory investigations for infection with hepatitis a , b , and c viruses and serology for cytomegalovirus and epstein - barr virus were negative . methotrexate was stopped , and therapy with oral methylprednisolone ( 80 mg / day ) was initiated . a significant improvement in the following parameters was observed a week later : prothrombin time ( 88% ) , asat 270 u / l , alat 340 u / l , s. gamma - gt 122 iu / l , and s. alkaline phosphatase 173 iu / l . after 4 months , all laboratory parameters had normalized , and serum was negative for antimitochondrial and antinuclear antibodies . patients taking mtx are more likely to discontinue therapy because of adverse drug effects rather than because of lack of efficacy . adverse effects of mtx are , usually , mild and self - limiting , but may include serious adverse drug reactions such as hematopoietic suppression , pulmonary , and hepatotoxicity . hepatic fibrosis is a usual adverse reaction reported with long - term use of mtx therapy in psoriatic patients . causality assessment of the adverse drug event ( ade ) was carried out using who - umc criteria , naranjo 's scale , and roussel uclaf causality assessment method ( rucam ) scale . in this case , patient improved on withdrawal of the drug , and there were no other confounding factors that could have caused this adverse effect . hence , the ade was probably caused by mtx ( who - umc criteria : probable ; naranjo 's score : 7 , probable ; and rucam scale : 5 ) . in addition , sufficient and continuous exposure to the drug , lack of previous evidence of autoimmune disease and complete resolution of the condition within 4 months of discontinuation of the suspected drug confirmed the diagnostic criteria of drug - induced autoimmunity . the first case of autoimmune hepatitis associated with mtx was described in 2011 in a 57-year - old man after 11 years of treatment with mtx . a complete normalization of laboratory parameters was obtained 5 months after stopping this drug . to the best of our knowledge , it , usually , occurs at higher doses and also positively correlates with the cumulative dose of drugs . other risk factors for the development of elevated liver enzymes and changes in liver biopsy include obesity , higher alcohol intake prior to commencement of mtx and persistent hepatitis b or c infection . in the present case , appearance of autoantibodies and transitory autoimmune disease associated with infliximab in a patient with psoriatic arthritis has also been documented and the preexistent serological signs of autoimmunity are believed to be a risk factor for the development of similar autoimmune reactions . this report confirms the need to monitor liver enzymes carefully in patients with psoriatic arthritis using long - term treatment with mtx . clinicians must collaborate with the pharmacovigilance center to detect and notify serious adverse effects of mtx . further research is needed to identify the exact mechanism and establish , if possible , primary means of prevention of this serious adverse effect .
methotrexate ( mtx ) is one of the most commonly used medicines in the treatment of psoriatic arthritis . 
 the drug can produce steatosis and cirrhosis . 
 autoimmune hepatitis is a rare and serious adverse effect . 
 we describe the case of a 53-year - old woman who developed autoimmune hepatitis after a long - term use of mtx for psoriatic arthritis . 
 hepatitis was completely resolved 4 months after stopping this drug . 
 the pathophysiologic mechanisms of a drug - induced autoimmunity are unclear and complex . 
 this report confirms the need to monitor liver enzymes carefully in patients using long - term treatment with mtx for psoriasis or rheumatoid arthritis .