Pseudocyst or cystic neoplasm? Differential diagnosis and initial management of cystic pancreatic lesions.

Owing to advances in pancreatic imaging, cystic lesions of the pancreas are being recognized with increasing frequency. A presumptive diagnosis of "pseudocyst", based upon CT appearance alone, will prove to be in error in as many as one-third of patients. Neoplastic cysts of the pancreas are particularly susceptible to this misdiagnosis, which can result in inappropriate drainage rather than resection. Using a combination of historical features and computed tomography, the differential diagnosis between pseudocyst and cystic neoplasm can usually be made. In borderline patients transcutaneous aspiration for cytology, and analysis of the cyst fluid for neoplastic markers may prove helpful. Final resolution of doubtful cases is achieved by biopsy of the cyst wall.