Autoimmune Hepatitis Induced by Hepatitis Delta Virus: A Conundrum.

Introduction: The association of hepatitis delta virus (HDV) infection with positive autoantibodies and autoimmune features has been known for decades. However, to date, very few cases of clinical autoimmune hepatitis (AIH) have been reported in association with HDV infection, most of them being in the context of treatment with peginterferon. Case Report: This case refers to a 46-year-old woman born in Guinea-Bissau who moved to Portugal in 2018 to investigate complaints of diffuse abdominal discomfort and nausea. Her initial work-up, including laboratory and liver histology, was consistent with type 1 AIH. She had HBe antigen-negative chronic hepatitis B virus infection with negative DNA and also a positive total anti-HDV antibody, with negative IgM and undetectable RNA. Therefore, after initiating prophylactic tenofovir difumarate, she was started on prednisolone followed by azathioprine, which was later stopped due to presumed hepatotoxicity. Repeated histology showed signs of viral superinfection, and she was treated with acyclovir due to a positive herpes simplex IgM, with HDV RNA remaining negative. A third flare in transaminases prompted the introduction of mycophenolate mofetil (MMF) after a thorough exclusion of additional causes of liver disease. About 6 months later, during another bout of hepatitis, HDV RNA was finally positive and classified as genotype 5. MMF was stopped, and, considering a contraindication to interferon, the patient was offered therapy with bulevirtide, which she refused for personal reasons as she is currently living in her home country. Discussion: This is a challenging case of autoimmune or "autoimmune-like" hepatitis, probably induced by chronic HDV infection. High suspicion of HDV was essential because, had the case been interpreted as refractory AIH, with escalation of immunosuppression, a more severe course of the viral infection might have ensued. Recently, HDV suppression with bulevirtide was shown to reverse autoimmune liver disease. We hypothesize that the same could have happened to our patient, had she accepted this treatment.