Case report of a mature cystic teratoma in the tail of the pancreas in a 54-year-old male.

Background: Pancreatic dermoid cyst (also referred to as mature cystic teratoma) is a rare, histologically well-differentiated benign germ cell tumor. Preoperative definitive diagnosis remains challenging due to the absence of specific imaging features and reliable serum tumor markers. Case description: We present a case of a 54-year-old male patient in whom a cystic low-density lesion, measuring 3.08 cm × 2.82 cm × 2.82 cm with predominantly well-defined margins and relatively homogeneous density, was incidentally detected in the pancreatic tail during a routine physical examination. Preoperative imaging assessment indicated a cystic neoplasm; however, its benign or malignant nature could not be definitively ascertained. The initial preoperative plan under general anesthesia included laparoscopic exploration and abdominal mass resection, with a contingency plan for combined distal pancreatectomy and splenectomy. During the operation, the chief surgeon observed with the naked eye that the mass had a complete capsule and was only closely adhered to the tail of the pancreas, making it easy to resection. Therefore, the surgery was adjusted to laparoscopic pancreatic lesion resection combined with percutaneous abdominal drainage. Postoperative pathological examination confirmed it to be a cystic mature teratoma. Given the potential malignant risk associated with such lesions, regular postoperative imaging follow-up was scheduled to evaluate treatment outcomes. To date, the patient has completed over 10 months of postoperative follow-up with no evidence of recurrence. Conclusion: Pancreatic dermoid cysts are extremely rare, and their diagnosis depends on postoperative pathological examination. Although preoperative confirmation remains challenging, this retrospective study underscores the diagnostic difficulties in imaging-based evaluation of pancreatic cystic lesions and systematically summarizes the current research advances and conceptual framework regarding these uncommon tumors. The findings may help prevent unnecessary extensive surgical resections resulting from misdiagnosis of pancreatic primary cystic neoplasms.