Müllerian Adenosarcoma of the Urinary Bladder: Clinicopathologic and Immunohistochemical Features with Novel Genetic Aberrations

Abstract

Müllerian adenosarcoma is a biphasic neoplasm most commonly of the uterus and less frequently of the ovary. It has been rarely described to occur in other sites such as peritoneum and liver. In this study, we report the clinicopathologic, immunohistochemical and molecular features of a primary müllerian adenosarcoma of the urinary bladder in a 62-year-old woman. To our knowledge, this is the first report of müllerian adenosarcoma primary to the urinary bladder in the literature. Light microscopy showed a biphasic epithelial and stromal tumor with benign-appearing glands surrounded by endometrial-type stroma that is densely cellular with increased mitotic figures. The stroma surrounding the glands is more cellular than the intervening areas, which are more loose and edematous. Immunohistochemistry profile included positive staining for Pax2/8 within the glands, for CD10 and WT-1 within the spindled stroma, and for estrogen and progesterone receptors in both. Staining for desmin, GATA3, p63, and human papilloma virus (HPV) is negative. Molecular analyses identified mutations in AKT1 E17K, FLT3 D835N, KRAS G12D and HRAS G12S. These novel molecular aberrations have yet to be reported in the medical literature. X chromosome inactivation analysis revealed a clonal pattern in the stromal component and a non-clonal pattern in the epithelial component. Currently, the patient is disease/recurrence-free after regular follow-up of approximately 84 months. This case represents the first reported diagnosis of müllerian adenosarcoma arising in the urinary bladder with extensive clinicopathologic, immunohistochemical, and molecular analyses.