Cystic fi broepithelioma of Pinkus: two new cases and cystic changes in classical fi broepithelioma of Pinkus
We report two new cases of cystic fi broepithelioma of Pinkus together with immunohistochemical features and analyze the presence of cystic changes in a series of 16 classical fi broepitheliomas of Pinkus. Our fi ndings show that the formation of cystic spaces is most probably caused by ischemic degeneration of stromal fenestrations, rather than by central tumor cell necrosis. Th is fi nding is supported by lack of CD34 positive blood vessels in edematous and hyalinized stromal fenestrations undergoing transformation into cystic spaces, as opposed to the uninvolved stromal fenestrations. Th erefore, it is probably more accurate to refer to this process as pseudocystic stromal degeneration rather than true cyst formation. Also, two out of 16 classical Pinkus fi broepitheliomas exhibited focal pseudocystic changes in 50 and 10 of the tumor, respectively, demonstrating that this degenerative process can be found, rarely and focally, in classical cases as well.