S3403 From Cancer Concern to Curable Infection: Pancreatic Tuberculosis With Biliary Obstruction Diagnosed via Endoscopic Ultrasound-Guided Fine Needle Biopsy

Introduction: Mycobacterium tuberculosis (TB) is an airborne, granulomatous infection that can involve both pulmonary and extrapulmonary sites. Pancreatic involvement is exceedingly rare and often mimics pancreatic malignancy, posing significant diagnostic challenges. We present an exceptional case of pancreatic tuberculosis causing obstructive jaundice, hepatic involvement, and biliary obstruction in an immunocompetent host. Diagnosis was established via endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP), with complete clinical resolution following antitubercular therapy. Case Description/Methods: A 30-year-old woman with recent immigration from Mexico presented with abdominal pain and jaundice. Laboratory evaluation revealed a total bilirubin of 3.3 mg/dL, AST 230 U/L, ALT 32 U/L, and alkaline phosphatase 327 U/L. Magnetic resonance imaging demonstrated a mass in the pancreatic neck, periportal lymphadenopathy, and multiple hepatic lesions, raising concern for metastatic pancreatic cancer. The patient underwent EUS with fine needle biopsy (FNB) which identified a 40 mm predominantly cystic mass in the pancreatic neck and periportal lymphadenopathy. Core biopsies of both a periportal lymph node and liver lesion revealed granulomatous inflammation, without malignant features. Acid-fast bacilli cultures from these specimens confirmed the diagnosis of TB. ERCP delineated a high-grade distal biliary stricture with upstream dilation for which plastic stent was placed for decompression. The patient was started on standard 4-drug antitubercular therapy. At 6 months, there was complete resolution of the pancreas mass, liver lesions, and lymphadenopathy, along with relief of the biliary obstruction. Discussion: Pancreatic tuberculosis is an uncommon manifestation of TB, even in endemic countries, and is particularly rare in immunocompetent individuals. When present, its location in the pancreas may necessitate EUS-guided tissue acquisition for diagnosis and ERCP for biliary decompression. EUS-FNB offers the advantage of obtaining core tissue with preserved architecture, which is essential for histopathologic evaluation. In the appropriate clinical context, a high index of suspicion is required, as cytopathologic samples must undergo mycobacterium staining and culture to establish the diagnosis. In this case, early recognition enabled timely initiation of antitubercular therapy, leading to complete clinical and radiographic resolution.