A 40-year-old Iranian female patient with no relevant past medical history underwent an abdominal ultrasound (US) during evaluation of mildly elevated liver enzymes, revealing an incidental mass in the caudate lobe. Magnetic resonance imaging (MRI) demonstrated a 3.5 × 2.8 cm caudate lesion with a central scar and high T2 signal, raising strong suspicion for fibrolamellar hepatocellular carcinoma (FL-HCC). Given the lesion’s deep location, percutaneous biopsy was deemed challenging, and an endoscopic ultrasound (EUS)-guided approach was recommended. EUS revealed a hypoechoic, hypervascular, oval mass measuring 32 × 27 mm with well-defined, smooth borders, located near the liver but with unclear site of origin. Fine-needle biopsies (FNB) were performed using a 22-gauge Acquire™ needle (Boston Scientific). Histopathology demonstrated a succinate dehydrogenase (SDH)-deficient paraganglioma  (Ki-67 3.8%). A DOTATATE PET/CT showed moderate uptake confined to the lesion with no evidence of metastases. Biochemical evaluation revealed elevated plasma normetanephrine at 3 nmol/L (normal <0.9 nmol/L), with normal chromogranin A. The patient reported only occasional night sweats without classical symptoms of catecholamine excess. Blood pressure remained stable throughout the evaluation, including after and during EUS-FNB. Given the functional nature of the tumor, surgical resection was advised. The patient is currently undergoing preoperative preparation with doxazosin.

Paragangliomas are rare neuroendocrine tumors that may present at any age and can cause secretory hypertension due to excessive catecholamine release. Most abdominal sympathetic paragangliomas arise from chromaffin tissue near the inferior mesenteric artery and the aortic bifurcation. Intra-abdominal paragangliomas are particularly uncommon, with an estimated incidence of 1 in 500,000. Diagnosis is typically established through plasma or urinary metanephrines and functional imaging, while tissue sampling is rarely performed due to bleeding and hypertensive risks.

This case highlights the diagnostic utility and safety of EUS-guided tissue acquisition for a functional abdominal paraganglioma. Despite the tumor’s biochemical activity, the patient tolerated EUS-FNB without hemodynamic instability, underscoring that EUS-guided biopsy may be considered in select cases where the diagnosis is unclear and histology is essential. To our knowledge, EUS-guided biopsy of an abdominal paraganglioma is exceedingly rare. This case emphasizes the importance of maintaining a broad differential for liver masses and demonstrates the expanding role of EUS-guided tissue sampling.