A Case of Primary Malignant Mixed Mesonephric Tumor of the Vagina.

Mesonephric adenocarcinoma is a clinically aggressive, rare malignant neoplasm characterized by mesonephric (Wolffian) differentiation. It can occur throughout the female genital tract; however, most cases arise in the uterine cervix. Vaginal mesonephric adenocarcinoma is uncommon, and cases with a concomitant sarcomatous component are extremely rare. Using appropriate immunohistochemistry, we present a rare case of a primary malignant mixed mesonephric tumor of the vagina, defined by biphasic epithelial and mesenchymal malignant components of mesonephric origin. The patient was a 34-year-old woman who presented with vaginal pain and bleeding. Pelvic examination and diagnostic imaging revealed a primary vaginal tumor measuring approximately 4 cm without distant metastases. Histological examination of the biopsy specimen revealed an adenocarcinoma with a sarcomatous component. Our initial diagnosis was primary vaginal carcinosarcoma; however, additional immunohistochemistry of the tumor revealed luminal membranous positivity for CD10, diffuse nuclear staining for TTF1, and estrogen receptor negativity. These findings led to a final diagnosis of a primary malignant mixed mesonephric tumor of the vagina. Because of the patient's young age and desire for fertility preservation, curative concurrent chemoradiation was performed after oocyte and ovarian cryopreservation and migration via laparoscopic surgery. The tumor showed a marked reduction in size within three months and remained under control. This case emphasizes the need for clinicians and pathologists to consider the possibility of a mesonephric origin when encountering vaginal adenocarcinoma with a sarcomatous component. Appropriate immunohistochemical analysis is essential for establishing an accurate diagnosis and developing effective therapeutic strategies.