Vaginal Angioleiomyoma in a Dog: A First Case Report

Vaginal tumors are relatively uncommon in dogs and are predominantly benign mesenchymal neoplasms, such as leiomyomas and fibromas. Among perivascular wall tumors, angioleiomyoma is a rare benign neoplasm characterized by welldifferentiated smooth muscle bundles interspersed with numerous blood vessels. While typically arising from the dermis or subcutis, a genital origin is exceptionally rare in veterinary medicine. A 15-year-old intact female Maltese dog presented with a pedunculated vaginal mass. The mass was surgically excised along with a concurrent ovariohysterectomy. Histologically, the mass demonstrated a proliferation of neoplastic smooth muscle cells appearing to arise from the blood vessel walls and expanding into the adjacent stroma. The neoplastic cells were fusiform with cigar-shaped nuclei and lacked atypia or mitotic figures. Immunohistochemically, the neoplastic bundles were diffusely positive for vimentin and alpha-smooth muscle actin, and multifocally positive for desmin, while negative for von Willebrand factor. Based on these findings, the mass was diagnosed as a vaginal angioleiomyoma. Clinically, the rich vascular network of this tumor may necessitate thorough hemostasis during surgery. Furthermore, the successful management with OHE suggests a potential hormonal influence on its pathogenesis. To the best of the authors’ knowledge, this represents the first report of vaginal angioleiomyoma in a dog, providing valuable diagnostic insights into the morphological diversity of canine perivascular wall tumors.