surgical treatment of hemangiopericytoma in the lip of a filly: a clinical report

Case description: a 1.5-year-old filly weighing approximately 150 kg was presented to the clinic for a dense tumor-like mass on her lower lip. clinical findings: according to physical examinations, it was observed that the filly had a solitary, well-circumscribed, red or pinkish mass of 7 × 5 × 3.5 cm. palpation caused pain in the mass; however, no other physical abnormality was detected. radiological diagnosis: radiographs indicated a well-circumscribed, focally mineralized, non-invasive to muscle layer mass without signs of further bone invasion and periosteal reaction. treatment and outcome- surgical removal of the mass was applied under general anesthesia. histological examination revealed that the tumor contained spindle-shaped cells surrounding the endothelial- lined vascular spaces. neoplastic cells were arranged in short interlacing bundles and storiform whorls were randomly distributed throughout a fibrous or myxoid stroma. neoplastic cells formed many whorls separated by spacious stromal collagen. eight months after surgical excision, the filly was reexamined and no evidence of lip mass recurrence was observed. clinical relevance- hemangiopericytomas poorly respond to chemotherapy and radiotherapy and complete surgical resection is the only effective therapy for hemangiopericytoma.