Introduction

Pyrexia of unknown origin (PUO) remains a diagnostic challenge with a broad differential that includes infection, malignancy, non‐infectious inflammatory disease, and miscellaneous causes. In many adults, the final diagnosis depends on a stepwise, clue‐driven approach, with repeated clinical assessment and selective use of advanced imaging rather than depending on the initial presentation alone [1]. Acute cholangitis is a significant and treatable infection, yet the classical Charcot triad of fever, jaundice, and right upper quadrant pain has limited sensitivity [2]. When cholangitis presents without localizing biliary symptoms, diagnosis may be delayed, and complications such as septic portal vein thrombosis (pylephlebitis) can occur [3, 4]. Biliary‐source pylephlebitis is rare, and progression to cavernous transformation with portal biliopathy makes the presentation even more unusual [3, 4, 5, 6, 7].

We report a middle‐aged man who presented with prolonged fever, weight loss, portal hypertensive changes, and preserved liver stiffness, in whom advanced imaging ultimately revealed occult cholangitis complicated by portal vein thrombosis and cavernous transformation.