Autoimmune hepatitis in a patient with thymectomy: the benefit of histology and MUM-1 immunostaining

A 61 years-old female patient, with a history of myaesthenia gravis since 1992, for which she underwent a thymectomy and is treated by pyridostigmine 60 mg once daily, was referred to our outpatient clinic by her general practioner for symptoms of nausea, lack of appetite and pyrosis. Abdominal clinical examination and upper gastrointestinal tract endoscopy were normal. Routine biological testing showed an important liver enzyme perturbation, with a typical hepatocellular injury pattern: aspartate aminotransferase level (AST) at 1449 U/L, alanine aminotransferase level (ALT) at 1856 U/L, alkaline phosphatase level (ALP) at 211 U/L, gamma-glutamyl transpeptidase level (GGT) at 211 U/L, lactate dehydrogenase level (LDH) at 796 UI/L, total bilirubinemia was 5.85 mg/dL, direct bilirubinemia was 5.18 and ferritinemia was above 2000 ng/ml. Peripheral blood cells showed 2670 leucocytes/µL (with 46.3% of neutrophils and 25.7% of lymphocytes). Abdominal ultrasound was normal.