Non-neoplastic cystic and cystic-like lesions of the pancreas: may mimic pancreatic cystic neoplasms

BACKGROUND: Cystic lesions of the pancreas consist of a broad range of pathological entities. With the exception of the pancreatic pseudocyst, these are usually caused by pancreatic cystic neoplasms. Non-neoplastic pancreatic cystic and cystic-like lesions are extremely rare. In the present article, the surgical experience with these unusual entities over a 14-year period is reported. METHODS: Between 1991 and 2004, all patients who underwent surgical exploration for a cystic lesion of the pancreas were retrospectively reviewed. Patients with a pancreatic pseudocyst were excluded. There were 106 patients of whom 8 (7.5%) had a final pathological diagnosis consistent with a non-neoplastic pancreatic cystic or cystic-like lesion, including 3 patients with a benign epithelial cyst, 2 with a pancreatic abscess (one tuberculous and one foreign body), 2 with mucous retention cysts and 1 with a mucinous non-neoplastic cyst. These eight patients are the focus of this study. RESULTS: There were six female and two male patients with a median age of 61.5 years (range, 41-71 years). All the patients were of Asian origin including seven Chinese and one Indian. Four of the patients were asymptomatic and their pancreatic cysts were discovered incidentally on radiological imaging for other indications. All the patients underwent preoperative radiological investigations, including ultrasonography, computed tomography or magnetic resonance imaging, which showed a cystic lesion of the pancreas. Three patients, all of whom were symptomatic, were diagnosed preoperatively with a malignant cystic neoplasm on the basis of radiological imaging. Two patients were eventually found to have a pancreatic abscess, one tuberculous and the other, secondary to foreign body perforation. The third patient was found on final histology to have chronic pancreatitis with retention cysts. The remaining five patients had a preoperative diagnosis of an indeterminate cyst; on pathological examination, they were found to have a benign epithelial (congenital) cyst (n = 3), retention cyst (n = 1) and mucinous non-neoplastic cyst (n = 1). At a median follow up of 20 months (range, 3-34 months), none of the patients had any evidence of recurrent disease. CONCLUSION: Non-neoplastic cystic and cystic-like lesions of the pancreas are rare causes of pancreatic cystic lesions that are generally benign and do not require surgery when asymptomatic. However, despite advances in diagnostic investigations such as endoscopic ultrasound with fluid aspirate and magnetic resonance imaging, the preoperative diagnosis remains unreliable. Hence, the challenge for all clinicians is to recognize these lesions preoperatively and to avoid 'unnecessary' surgery.