A 51-year-old male presented to the emergency department with acute back pain, suspicious for renal colic. An abdominal CT scan incidentally revealed a 30 mm hypodense lesion in the pancreatic uncinate process with central calcifications. An endoscopic ultrasound (EUS) demonstrated a hypoechoic, heterogeneous mass in the uncinate process, with irregular margins and a huge posterior acoustic shadowing. No signs of vascular or ductal involvement were noted. Therefore, EUS-guided fine needle biopsy (FNB) with a 22-G Franseen-tip needle was performed via transduodenal and transgastric approaches, obtaining an adequate histological sample after macroscopic on-site examination (MOSE).Histological analysis revealed spindle cells positive for CD34, BCL2, STAT6, and CD99, and negative for CKIT, DOG1, desmin, actin, S100, and cytokeratins, with Ki-67 index > 5%, suggesting for solitary fibrous tumor (SFT) of the pancreas. Immunohistochemical confirmation was obtained at a tertiary referral pathology laboratory. A multidisciplinary tumor board advised conservative follow-up based on the benign histology and absence of local invasion.

Conclusion: Pancreatic SFTs are extremely rare, with only 34 cases reported to date (2). They are more frequently located in the pancreatic head and are slightly more common in females (2). Most are discovered incidentally (2). This case highlights the critical diagnostic value of EUS-FNB, which enabled accurate tissue acquisition for advanced immunohistochemical analysis, informing a nonsurgical, surveillance-based approach. Because of the non-specific clinical presentation and radiological features of pancreatic SFTs, diagnosis is particularly challenging using preoperative imaging and laboratory tests alone (1,2). Therefore, histopathological and immunohistochemical evaluation is essential for definitive diagnosis (1).