A case report describes a 59-year-old man with IgG4-related sclerosing cholangitis who underwent resection of a hilar lesion and Roux-en-Y hepaticojejunostomy for obstructive jaundice 7 years ago, with a diagnosis of IgG4-SC confirmed by postoperative pathology. From the 4th month after the operation, the patient had repeated episodes of fever, which persisted for 7 years and clinically corresponded to the so-called sump syndrome. Recurrent infections together with IgG4-SC activity may have increased IgG4 levels, making it difficult to assess whether this was a flare-up of the underlying disease or a response to the infection. Despite aggressive antibiotic treatment in combination with immunosuppressive therapy, episodes of infection recurred repeatedly. In August 2025, the patient died of sepsis, which arose in connection with recurrent cholangitis. The case highlights the need to differentiate IgG4-SC from hilar cholangiocarcinoma to avoid unnecessary radical surgery. At the same time, it points to the importance of distinguishing whether elevated IgG4 values after hepaticojejunostomy reflect disease activity or are a secondary consequence of infection, as this fundamentally affects the choice of treatment.