Müllerianosis and endosalpingiosis of the urinary bladder: report of two cases with review of the literature.

Müllerianosis of the urinary bladder is an extremely rare benign condition, characterized by the presence of a mixture of at least two müllerian-derived components, and endosalpingiosis is also an extremely rare condition, characterized by the presence of tubal-type epithelium. In this report, we describe the 17(th) case of müllerianosis and 5(th) case of endosalpingiosis of the urinary bladder. A 39-year-old Japanese female presented with menstrual hematuria and was found to have a polypoid lesion in the posterior wall of the urinary bladder. Histopathological study demonstrated variably-sized dilated tubular glands in the lamina propria and muscularis propria. These dilated glands were covered by ciliated cuboidal cells, and some of them were covered by columnar cells with intracytoplasmic mucin. Moreover, a tiny focus of endometrial tissues was also present. Immunohistochemically, these glandular cells were positive for estrogen receptor. Accordingly, a diagnosis of müllerianosis was made. The second case was a 37-year-old Japanese female, who was found to have a polypoid lesion in the posterior wall of the bladder. Dilated tubular glands were covered by ciliated cells in the lamina propria and muscularis propria. Neither endocervical nor endometrial tissues were observed. Immunohistochemically, these ciliated cells were positive for estrogen receptor. Accordingly, a diagnosis of endosalpingiosis was made. Our analysis revealed that these two conditions mainly affect premenopausal females and occur exclusively in the posterior wall. Although the pathogenesis remains completely unresolved, a metaplastic theory is favored. The recognition of these two conditions is important because they can mimic invasive adenocarcinoma.