Autoimmune hepatitis (AIH) is a chronic liver disease characterized by immune-mediated inflammation, necrosis, and potential progression to cirrhosis if not managed appropriately. This case report describes a rare presentation of AIH in a 16-year-old Nigerian adolescent with atypical features, including delayed menarche and bilateral leg swelling, but without jaundice which is a common symptom of liver dysfunction. The patient was initially misdiagnosed with other conditions before being correctly identified as having Type 1 Autoimmune Hepatitis following appropriate diagnostic evaluation, which included liver function tests, imaging, and autoantibody tests. She responded favourably to treatment with corticosteroids and azathioprine but her serum albumin remained low due to pre-existing cirrhosis. This case highlights the diagnostic challenges of AIH, particularly in resource-limited settings where diagnosis of infectious liver diseases often overshadows autoimmune conditions. The delay in diagnosis and treatment emphasizes the need for increased awareness and improved diagnostic resources in the sub-African region. Early intervention with immunosuppressive therapy is crucial for managing AIH and preventing progression to advanced liver disease. This report further emphasizes the importance of a high index of suspicion for AIH in adolescents with unexplained liver disease, even in the absence of classic symptoms.