Cystic
tumors of the pancreas form a heterogeneous group, with benign, premalignant, and malignant
tumors. The molecular events that underlie their neoplastic transformation process are poorly understood. Our purpose was to study
DNA ploidy by flow cytometry and p53
protein expression by immunohistochemistry in a large series of cystic
tumors of the pancreas. The series of 51 surgical specimens included 18
serous cystadenomas, 20 mucinous cystic
tumors (benign, n = 14; borderline, n = 1; malignant, n = 5), 10 intraductal papillary-mucinous
tumors (benign, n = 4; borderline, n = 1; malignant, n = 5), and 3 papillary and cystic
tumors. The p53
protein immunohistochemical study was done in all cases on deparaffinized sections stained with the
monoclonal antibody DO7.
DNA flow cytometry was performed in 31 cases on
formalin-fixed and paraffinembedded material. Neither p53
protein immunoreactivity nor
DNA aneuploidy was observed in any case of
serous cystadenoma. p53
protein overexpression was present in four of five malignant mucinous cystic
tumors but was absent in benign and borderline cases. Only one case of malignant mucinous cystic
tumor was
DNA aneuploid. All benign and borderline intraductal papillary-mucinous
tumors were p53 negative, and two of five malignant cases were p53 positive. There was no
DNA aneuploidy in any case of intraductal papillary-mucinous
tumors. The three cases of papillary-cystic
tumors showed neither p53
protein immunoreactivity nor
DNA aneuploidy. In cystic
tumors of the pancreas, p53
protein overexpression and
DNA aneuploidy are rare events, restricted to malignant cases, mostly
mucinous cystadenocarcinomas. Our results confirm that this group of
tumors is heterogeneous and underline the need for earlier markers of an aggressive behavior.