Human T-Lymphotropic Virus Type 1-Associated Myelopathy With Autoimmune Cholangiopathy: An Unusual Immune Conundrum in a Young Patient.

Human T-lymphotropic virus type 1 (HTLV-1), the first oncogenic retrovirus discovered in humans, is primarily associated with two disease entities: adult T cell leukemia-lymphoma and HTLV-1-associated myelopathy-tropical spastic paresis. HTLV-1 has also been implicated in the pathogenesis of various autoimmune rheumatic diseases, and its association with the autoimmune disorders of the gastrointestinal track is less well understood. Our patient, a 26-year-old previously healthy female, presented with recurrent, progressively worsening chronic abdominal pain and persistent liver test abnormalities. Initially diagnosed with acute acalculous cholecystitis and autoimmune hepatitis (AIH), her liver tests continued to exhibit a predominantly cholestatic pattern. This prompted further advanced imaging, and magnetic resonance cholangiopancreatography ultimately confirmed a diagnosis of primary sclerosing cholangitis (PSC). Complicating her condition further, she developed lower extremity weakness, initially attributed to axonal Guillain-Barré syndrome, which unfortunately did not respond to standard treatment. After a year marked by progressive clinical decline with repeated and prolonged hospitalizations due to fever of unknown origin, an extensive diagnostic workup ultimately led to a diagnosis of HTLV-1 myelopathy, along with AIH-PSC overlap syndrome. This case highlights the diagnostic challenges associated with the multisystem involvement of HTLV-1. Notably, our patient's presentation was not consistent with classic HTLV-1 myelopathy rather a subtype with rapidly progressive symptoms and flaccid as opposed to spastic paresis. The association between HTLV-1 infection and autoimmune cholangiopathy is exceptionally rare. To the best of our knowledge, our case represents only the second reported instance of autoimmune cholangiopathy associated with HTLV-1 myelopathy and the first reported case of AIH-PSC overlap syndrome associated with HTLV-1 myelopathy. This underscores the need for heightened clinical awareness of potential hepatic immune manifestations in patients with HTLV-1 infection, even in the absence of classic neurologic symptoms at initial presentation.