Multimodality Imaging Features of Pancreatic Endometrioma Mimicking a Mucinous Cystic Neoplasm: Radiologic–Pathologic Correlation

Background: Pancreatic endometrioma is an exceptionally rare manifestation of extrapelvic endometriosis, with fewer than twenty well-documented cases reported in the literature. Because its radiologic appearance frequently overlaps with cystic pancreatic neoplasms, including mucinous cystic neoplasm (MCN), intraductal papillary mucinous neoplasm (IPMN), and pancreatic pseudocyst, accurate preoperative diagnosis remains extremely challenging. Purpose: To describe the multimodality imaging characteristics, surgical management, histopathologic findings, and differential diagnostic considerations of pancreatic endometrioma through radiologic–pathologic correlation. Methods: A 32-year-old woman with recurrent episodes of pancreatitis underwent multiphasic contrast-enhanced CT and comprehensive MRI for evaluation of a cystic lesion located in the pancreatic tail. Imaging findings were correlated with operative observations, gross pathology, histopathology, and immunohistochemical analyses following robotic spleen-preserving distal pancreatectomy. Results: CT and MRI demonstrated a well-circumscribed unilocular cystic lesion with mild peripheral wall enhancement, homogeneous T2 hyperintensity, T1 hypointensity, and no mural nodules, septations, diffusion restriction, or pancreatic duct communication. Because mucinous cystic neoplasm could not be confidently excluded, surgical resection was performed. Histopathologic examination revealed ectopic endometrial glands and endometrial stroma associated with chronic hemorrhage and hemosiderin-laden macrophages. Immunohistochemistry demonstrated diffuse CD10, estrogen receptor, and progesterone receptor positivity, confirming the diagnosis of pancreatic endometrioma. Conclusions: Pancreatic endometrioma should be included in the differential diagnosis of cystic pancreatic lesions in women of reproductive age, particularly in patients with recurrent pancreatitis or a history suggestive of endometriosis. Although definitive diagnosis currently relies on histopathologic confirmation, increased awareness of this rare entity and careful radiologic–pathologic correlation may improve preoperative diagnostic consideration and help optimize clinical management.