Inverted papilloma of the urinary bladder with granular eosinophilic cells. An unusual neuroendocrine variant.

We report the morphologic, immunohistochemical, and electron microscopic characteristics observed in a case of an inverted papilloma that contained neuroendocrine cells resected from the urinary bladder of a 77-year-old woman. Additionally, we evaluated the incidence of neuroendocrine cells in eight cases of inverted papillomas of the urinary bladder obtained from the files of the Armed Forces Institute of Pathology, Washington, DC. To our knowledge, an in-depth study of neuroendocrine cells in this neoplasm and a comparison of the same with neuroendocrine cells observed in other conditions in the lower genitourinary tract have not been previously published, prompting this report.