Gallbladder Agenesis in a Patient With Klinefelter Syndrome Presenting With Hematemesis and Right Upper-Quadrant Pain

BACKGROUND Gallbladder agenesis is a rare congenital anomaly resulting from failed cystic bud development or canalization during early embryogenesis. While frequently asymptomatic, up to half of patients develop postprandial right upper-quadrant pain resembling biliary colic. This report describes an unusual case of gallbladder agenesis in a 38-year-old man with Klinefelter syndrome who presented with hematemesis and right upper-quadrant pain. CASE REPORT A 38-year-old man with known Klinefelter syndrome (47, XXY) and no prior abdominal surgery presented with hematemesis, lightheadedness, syncope, and right upper-quadrant pain. Laboratory testing revealed mild transaminitis, elevated ferritin, and normal bilirubin. Computed tomography angiography initially revealed hepatic steatosis and splenomegaly, and no gallbladder was visualized on hepatobiliary iminodiacetic acid scan and ultrasound. Esophagogastroduodenoscopy showed mild antral gastritis and a small hiatal hernia without active bleeding. Gallbladder agenesis was confirmed by magnetic resonance cholangiopancreatography. The patient's hematemesis resolved spontaneously, and he was discharged in stable condition with hepatology follow-up. CONCLUSIONS This case highlights the diagnostic value of MRCP in confirming gallbladder agenesis and avoiding unnecessary surgical exploration. Hematemesis as the initial presentation is highly atypical, suggesting a potential but unproven link between gallbladder agenesis and upper-gastrointestinal bleeding. Additionally, this report presents the first known coexistence of GA and Klinefelter syndrome, raising the possibility of a subtle developmental correlation between chromosomal nondisjunction and endodermal organogenesis. Recognition of such rare presentations expands the phenotypic spectrum of Klinefelter-associated hepatobiliary abnormalities and underscores the need for awareness of gallbladder agenesis in patients with biliary-type pain but no visible gallbladder on imaging.