"Strings of pearls" appearance is seen in?

Chronic pancreatitis is characterized by irregularities of of the pancreatic ducts, ductal strictures, and area of duct dilation. The major as well as the side branch ducts may be involved. For unexplained reason, some patients with chronic pancreatitis develop dilated main pancreatic ducts (large ductal disease), whereas others retain ducts of normal or even smaller than normal calibers (small ductal disease). Some patients with chronic pancreatitis can be shown to have major ducts that have the appearance of a "chain of lakes" or a "strings of pearls" that is the result of segment of dilated duct separated by areas of ductal stricture. Ref: Sutton's Radiology 7/e, Volume 1, Page 798