Deep dermal and subcutaneous canine hemangiosarcoma in the perianal area: diagnosis of perianal mass in a dog

Background: Tumors of the perianal area occur frequently in dogs, and the two most common tumors are perianal gland adenoma and anal sac adenocarcinoma; others such as mast cell tumor, lymphoma and melanoma can also occur at this site. Diagnostic cytology is a useful technique and is usually used to establish a definitive diagnosis of some tumors in veterinary medicine. This report describes an extremely rare case of a deep dermal and subcutaneous canine hemangiosarcoma in the perianal area. Case presentation: A 13-year-old intact male spaniel was presented for evaluation of a 4 x 4 cm, ulcerated, and hemorrhagic mass presented in the right perianal region. In cytologic evaluation, malignant mesenchymal tumor with inflammation was diagnosed, and incidental heart worm microfilaremia was identified. Based on the cytologic evaluation, a punch biopsy (3 mm, three sites) was conducted under anesthesia and deep dermal and subcutaneous hemangiosarcoma (3 mitotic figures/10 high power field (400x)) was diagnosed by histopathological evaluation. It was also confirmed by immunohistochemistry results for cluster of differentiation 31 (CD31) and factor VIII-related antigen marker. Conclusions: Deep dermal and subcutaneous hemangiosarcoma in the perianal region is a rare condition, and its prognosis is usually poor. Perianal gland adenoma and anal sac adenocarcinoma are the two most common tumors in the perianal region, but other different types of tumors may also occur as in this case; therefore, accurate diagnosis is required using cytology and/or histopathological examination.