ANALYSIS OF SMALL CYSTIC LESIONS OF THE PANCREAS

There have been few reports on (1) the nature and pathogenesis of smal l cystic lesions of the pancreas, (2) their incidence, age distributio n, and location, and (3) their significance as potential precursors of intraductal papillary tumors, mucinous cystic tumors, and duct cell c arcinomas. Materials: Epithelial growth of small cystic lesions in 300 consecutive autopsy cases and in seven cases of small duct cell carci noma from among 2300 elderly autopsy cases, was evaluated by histopath ological analysis. One hundred eighty-six cystic lesions were found in 73 of 300 autopsy cases (24.3%). The incidence of cystic lesions incr eased with age. Cystic lesions were equally distributed throughout the pancreas. Epithelial atypia was histologically classified into five g roups: normal epithelium; papillary hyperplasia without atypia; atypic al hyperplasia; carcinoma in situ; and invasive carcinoma. The inciden ce of each group was 47.5, 32.8, 16.4, 3.4, and 0%, respectively. Epit helia of atypical hyperplasia or carcinoma in situ were more prevalent in small cystic lesions (less than 4 mm in diameter) than in larger l esions (chi-square test, p < 0.05). Epithelia of dilated ductular bran ches adjacent to cystic lesions showed a similar degree of atypia as t he epithelia of the cystic lesions themselves (p < 0.01). Epithelial a typia of the main pancreatic duct was mild in all of the cases but two , and was not related to that of the cystic lesion. Among the seven ca ses of small duct cell carcinoma, two cases had small cancerous cystic lesions, 4.1 and 5.3 mm in diameter, within the tumor. Small cystic l esions appear to have the potential to progress to malignancy but defi nitive evidence has not been demonstrated. Additional studies, includi ng molecular biological examinations, are necessary to fully understan d the biology of these lesions.