Biliary tuberculosis (BTB) is an uncommon extrapulmonary manifestation of tuberculosis^[8]. It can develop through three distinct pathways: (i) descending infection from portal tracts into the bile ducts, (ii) periportal lymphadenitis due to TB, and (iii) ascending infection from the Vater ampulla^[9]. The symptoms of biliary tuberculosis often result from strictures caused by primary tuberculosis of the biliary tract, post- ATT effects, rupture of caseating granulomas into the bile ducts, compression from tuberculous adenitis associated with periportal, pericholedochal, or peripancreatic lymph nodes, or from a pseudotumor^[9]. Previous reports of biliary stricture due to bile duct tuberculosis are extremely rare^[10]. In comparison with previously published cases, our patient similarly presented with vague abdominal symptoms and recurrent strictures that mimicked malignancy. However, unlike some reports where diagnosis was established through lymph node FNA or earlier tissue sampling, this case required multiple interventions and ultimately relied on positive CBD brushing to reach a diagnosis, making it one of the more diagnostically delayed presentations in literature. The diagnosis of biliary TB can become challenging due to its nonspecific symptoms as in our case, the patient’s recurrent biliary strictures and non-specific symptoms such as abdominal pain, weight loss, and nausea, along with negative malignancy results from multiple biopsies, posed a significant diagnostic challenge. An important limitation in this case was the initial failure of both lymph node FNA and multiple biopsy samples to detect TB, likely due to the patchy or localized involvement of the disease. These false-negative results significantly delayed appropriate treatment and underscore the low sensitivity of conventional histopathology and cytology in detecting M. tuberculosis in biliary tissues. The difficulty in diagnosing BTB can further increase by the overlapping clinical and radiological features with other biliary pathologies, such as cholangiocarcinoma and primary sclerosing cholangitis when hepatic granuoloma becomes involved leading to nuemerous complex strictures^[11].

Preoperative diagnosis of BTB is crucial as it significantly influences management strategies. Accurate identification of BTB allows for conservative treatment options, such as the use of stents and ATT, which can effectively manage the condition without the need for more invasive surgical interventions^[10]. In this case, despite multiple stent placements and ERCP procedures, the diagnosis remained unclear until CBD brushing during ERCP finally revealed M. tuberculosis. Biliary brushing during ERCP plays a pivotal role in diagnosing BTB. ERCP allows for the collection of biliary aspirates for AFB staining or culture, and FNA of adjacent lymph nodes if necessary. With the development of these strategies tissue diagnosis can be established based on suspicion of the disease, negating the need for a laparotomy in the diagnosis of hepatobiliary TB^[5].

Routine liver function tests typically do not provide significant diagnostic insights for BTB, as they often remain within normal ranges^[3]. However, imaging techniques can offer additional clues. Abdominal X-rays may reveal calcifications in about 50% of hepatic BTB cases, presenting as “chalky” and confluent calcifications along the course of the CBD^[12]. Ultrasonography may show dilated intrahepatic ducts or CBD^[3]. Pathological examination of bile duct specimens in BTB typically reveals multiple small cavities filled with greenish necrotic material, bile pigment, and caseation as in this patient whose pathological specimen showed multiple granulomas^[9]. A valuable addition to the diagnostic toolkit in such cases is molecular diagnostics, such as polymerase chain reaction (PCR) for TB DNA. This technique can significantly improve the preoperative detection of M. tuberculosis, especially in smear-negative or paucibacillary cases, and may help avoid delays or unnecessary surgeries. Identifying TB DNA in blood and bile specimens through molecular assays before surgery can further aid in the preoperative diagnosis^[10]. Preoperative diagnosis enables timely initiation of ATT and appropriate biliary decompression techniques, such as transhepatic biliary drainage or stenting, reducing the need for more invasive surgical procedures^[10]. For patients with biliary stones, cholecystectomy combined with ATT is often required^[13]. The standard treatment regimen for TB includes a combination of isoniazid, rifampin, ethambutol, and pyrazinamide, typically administered over a 6 to 9-month period.