Hemangiopericytoma in dogs (CHP) is a soft tissue neoplasm that originates from the pericytes or subcutaneous perivascular cells, and is often seen on the limbs as limited solid nodules. The microscopic characterization of this type of neoplasm is spindle-shaped cells with the cytoplasmic process which are arranged in whorls around the blood vessels, and the neoplastic cells form a “fingerprint” pattern. A three year-old Sarabi male dog with a very large, firm, greyish-white mass measuring 23 × 18 × 13 cm on the right side of the face, attached to the ear was referred to the surgery department of the Veterinary Teaching Hospital of Ferdowsi University of Mashhad. The surface of the mass was ulcerative. Most parts of the mass had a necrotic appearance. After preparing the animal, the mass was excised surgically. Due to the large size and weight of the mass, excision was performed in several stages using monopolar electrocautery. After incising the mass and its intact margin, due to probable vertical ear canal involvement, it had been resected with the Vertical Ear Canal Ablation technique, too. Finally, for histopathological evaluations, samples were sent to the pathology department. The proliferation of spindle-shaped cells around the capillaries and the perivascular whorls were seen. Also, mild infiltration of inflammatory cells and fibroplasia were observed. Finally, on the basis of histopathological findings, the mass was diagnosed as canine hemangiopericytoma. After the surgery, the patient’s health status was monitored for up to three months and no signs of metastasis had been observed in examinations, and the outcome of the surgery seems satisfying.

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