Intralobular distribution of ovarian-like stroma in pancreatic mucinous cystic neoplasms: a discussion on its tumorigenesis

Abstract Pancreatic mucinous cystic neoplasm (MCN) has two histological components: tumor epithelia and ovarian-like stroma (OLS). To examine the progression and changes in pancreatic MCNs, we analyzed the distribution, amount, immunohistochemical phenotype, presence of theca cells of OLS, and tumor epithelium in 45 surgically resected MCN cases, comparing them with tumor sizes. The OLS data of female MCN cases were also compared between those who were ≤ 51 years old and those > 51 years old to see the effect of menopause on MCN histology. Non-mucinous type epithelium was present in all low-grade MCNs, but its ratio decreased with tumor size (p 51 years than those ≤ 51 years old, however it did not reach statistical significance. This is the first study to show the intralobular distribution of OLS.