A 32 year old lady presents with a 4 month history of tiredness, upper abdominal discomfort and arthralgia. On examination, she has hepatomegaly and jaundice. You request a liver screen blood test, which reveals that her ALT is 270 U/L (normal less than 35 U/L), AST is 256 U/L (normal less than 35 U/L), Alkaline Phosphatase is 156 U/L (normal range, 30-130 U/L), Anti-Smooth Muscle Antibody is positive, Anti-Mitochondrial Antibody is negative and Liver-Kidney Microsomal Antibody is negative.
What is the most likely diagnosis?