A common tumor in an uncommon site: epithelioid Leiomyoma arising from the seminal vesicle-a case report.

Background: Leiomyoma of the seminal vesicle is a rare leiomyoma characterized by the formation of benign leiomyomatous tissue within the seminal vesicle. Although histologically benign, excessive size can lead to urinary system disease if left untreated. Herein, we report a case of a seminal vesicle epithelioid leiomyoma.

Case Presentation: A 36-year-old Chinese man sought medical attention at our hospital for urination pain and hemospermia. CT showed a 5.3 cm × 5.0 cm seminal vesicle mass with a mixed density in the right seminal vesicle. The gross specimen showed light yellow, gray, and white tissues, with softness and hemorrhage in some places. Histologically, it showed classic spindle cell proliferation, with spindle cells arranged in fascicles, and mitosis was rare. Immunohistochemistry showed frequent expression of smooth muscle markers, such as calponin, SMA, and desmin. A diagnosis of epithelioid leiomyoma was proposed according to the immunohistochemical findings and morphology. The patient did not receive adjuvant therapy. There was no evidence of tumor recurrence in the 10 months after surgery.

Conclusions: We report the first case of epithelioid leiomyoma in the seminal vesicle. This disease should be included in the differential diagnostic list of seminal vesicle tumors with epithelioid morphology.