Cancer in Situ in Pancreatic Squamous Metaplasia

Although squamous metaplasia of the pancreatic ducts is not uncommon, being found in 9% to 64% of pancreases routinely examined at necropsy,1,2squamous cell carcinoma of this organ is rare. Only 8 cases have been documented.3-8Sommers and Meissner9failed to encounter such a lesion in a review of 142 cases of pancreatic carcinoma, although 5 instances of adenocanthoma were observed. Lowry and associates7and Lawrence6noted squamous metaplasia of the pancreatic ducts in their solitary case reports of primary pancreatic squamous cell carcinoma, and they postulated that the tumor developed from areas of squamous metaplasia, although this transition was not demonstrated. Wolbach and Howe,10in 1925, noted focal changes in areas of squamous metaplasia of pancreatic ducts in vitamin-deficient rats which changes they considered to be early carcinoma. Similar changes considered to represent in situ carcinoma in areas of squamous metaplasia have not