Nodal metastasis from an occult duodenal gastrinoma amid an overlap of xanthogranulomatous and type 1 autoimmune pancreatitis: A case report.

Gastrinomas are uncommon neuroendocrine tumors (NETs) that often present as occult primary lesions. Their coexistence with xanthogranulomatous pancreatitis (XGP) and type 1 autoimmune pancreatitis (AIP) is exceptionally rare. Here, we report the case of a 69-year-old man who presented with acute epigastric pain. Initial computed tomography (CT) revealed a 5.5-cm minimally enhancing pancreatic head mass with fat stranding and regional lymphadenopathy. Magnetic resonance imaging showed peripheral T1 hyperintensity without solid enhancement, suggesting an inflammatory or hemorrhagic lesion. Endoscopic ultrasound-guided fine-needle aspiration biopsy was suggestive of a NET. However, 68Ga-DOTATOC positron emission tomography-CT demonstrated no somatostatin receptor (SSTR) uptake in the pancreatic mass but intense uptake in a regional lymph node. Follow-up CT showed interval reduction (3.5 cm) with rim enhancement, further supporting an inflammatory lesion. Pancreaticoduodenectomy was performed. Histopathologically, the pancreatic head mass exhibited overlapping features of XGP and type 1 AIP. Additionally, a 0.6-cm occult duodenal gastrinoma with nodal metastases was identified. This case emphasizes that SSTR-avid nodal disease with an SSTR-negative pancreatic mass warrants meticulous duodenal evaluation. The rare coexistence of XGP and type 1 AIP expands the spectrum of inflammatory pancreatic lesions that mimic neoplasms, highlighting the importance of integrating multimodality imaging with histopathologic correlation.