'Ovarian-type' stroma of pancreatic mucinous cystic tumor expresses smooth muscle phenotype.

'Ovarian-type' stroma of nine mucinous cystic tumors (MCT) of the pancreas, six cystadenomas and three cystadenocarcinomas, were studied immunohistochemically. Most of the spindle cells of the 'ovarian-type' stroma were positive for smooth muscle actin and desmin, but were negative for S-100 protein, cytochrome P450 19 and CD34. Similar stroma with smooth muscle differentiation has been described in hepatobiliary MCT. Embryologic similarity between the pancreas and liver suggests a closely related origin of MCT in both organs.