The beta form of the estrogen receptor is predominantly expressed in the papillary cystic neoplasm of the pancreas.

Introduction: Papillary cystic neoplasm (PCN) of the pancreas is a low-malignancy tumor affecting predominantly young females. Sex steroid hormones have been involved in its development and/or growth. Estrogen receptor (ER) has been scarcely found in this tumor, although there is some evidence suggesting expression of the beta-isoform. Unlike ER, progesterone receptor (PR) expression has been consistently observed. Immunohistochemical analysis of the two isoforms of ER has not been performed in this tumor.

Aim: To characterize expression of ER isoforms with an immunohistochemical method.

Methodology: Expression of ER-alpha, ER-beta, and PR was analyzed by immunohistochemistry using isoform-specific ER and PR antibodies in paraffin-embedded tissue blocks from seven cases of PCN of the pancreas.

Results: Most patients were young females. ER-alpha and ER-beta were present in two and six tumors, respectively. PR was identified in six tumors.

Conclusions: ER-beta expression predominates over the alpha-isoform in PCN of the pancreas. This finding supports the idea that previous negative results on ER expression were a consequence of the use of antibodies with no anti-beta activity. The role of ER-beta in the milieu of factors promoting the development and aggressiveness of PCN needs to be elucidated to address novel diagnostic and therapeutic approaches.