Endoscopic ultrasonography in the diagnosis of chronic pancreatitis.

Endoscopic ultrasonography (EUS) is highly accurate in the diagnosis of chronic pancreatitis. Both parenchymal and ductal changes indicative of chronic pancreatitis can be identified. Parenchymal changes include small cystic abnormalities and hyperechoic foci scattered throughout the gland; the entire gland may be enlarged in early chronic pancreatitis, or small and atrophic in advanced disease. Ductal changes include enlargement of the main pancreatic duct or secondary branches, and the presence of stones or proteinaceous plugs within the ducts. Pseudocysts appear as cystic structures of mixed echogenicity; EUS is able to detect small pseudocysts or masses not identified by conventional imaging modalities. EUS has some difficulty in distinguishing benign from malignant pancreatic masses, particularly when the lesions are small. EUS should not supplant the use of CT scan or ERCP in the differential diagnosis of pancreatic disease, but is rather an adjunct to these studies. Future clinical research should focus on determining the appropriate indications for EUS in pancreatic disease, and determining if patient outcomes are favorably affected by the diagnostic information obtained.