Mixed epithelial and stromal tumor of the seminal vesicle: A case report and literature review.

A mixed epithelial and stromal tumor of the seminal vesicle gland is an uncommon neoplasm characterized by a dual population of epithelial and stromal cells. In this case report, we present a 59-year-old male patient who presented with a large, 10 cm mass in the left seminal vesicle, which was preliminarily suspected to be a malignant tumor of the seminal vesicle based on magnetic resonance imaging findings. Histopathological evaluation, however, revealed a tumor with biphasic epithelial-mesenchymal differentiation, predominantly displaying mesenchymal characteristics. The epithelium and stroma displayed papillary and foliar structures, respectively. The epithelial cells were bland, arranged in either single or multi-layered cuboidal patterns, and the stromal cells were spindle shaped with a sparse distribution. The patient experienced a favorable postoperative outcome. The diagnosis of mixed epithelial and stromal tumor is challenging based on clinical and imaging findings alone, and definitive diagnosis relies on pathological examination. This case report addresses a rare presentation of low-grade mixed epithelial and stromal tumor in the seminal vesicle gland and aims to expand the understanding of this entity by reviewing the relevant literature.