Unusual vaginal angiomatous neoformation in a 3-year-old pug

A 3-year-old female pug (8 kg bodyweight) was referred by a local veterinarian for evaluation of vaginal bleeding. Historically, the owner indicated chronic haematic vaginal discharge initiated approximately 3 months ago, overall good appetite and slight general dullness. Two months prior to the visit, the bitch had been spayed by the local veterinarian, but vaginal bleeding persisted after surgery. Following a general examination and complete blood analysis, a genital tract examination was performed and, through vaginal endoscopy, a red, smooth, and apparently broad-based vaginal mass was found. An episiotomy was performed and on surgical exploration, the bleeding site was determined to be on the surface of a mass composed of two congested, adjacent cylindrical structures, symmetric to the vaginal sagittal midline, broadbased and quite regular on the surface. The mass appeared to be well delimited from the surrounding tissue by a thin capsula, and each cylindrical structure had a tributary vessel. Ectopic and dysplastic corpora cavernosa of the clitoris characterized by angiomatous proliferation, cavernous haemangioma and vascular hamartoma were considered in the differential diagnosis. The presence of small intralesional nerves identified by S100 immunostaining was used as a diagnostic clue to classify this unusual vaginal angiomatous neoformation as vascular hamartoma.