Parapharyngeal space hemangiopericytoma treated with surgery and postoperative radiation--a case report

Hemangiopericytoma (HPC) is a rare tumor of uncertain malignant potential arising from mesenchymal cells with pericytic differentiation. It accounts for 3-5% of soft tissue sarcomas and 1% of vascular tumors. It usually presents in 5th to 6th decade of life. Most common sites are limbs, pelvis and head and neck. About 20% of all hemangiopericytomas are seen in head and neck, mostly in adults. Usually it presents in orbit, nasal cavity, oral cavity, jaw, parotid gland, parapharyngeal space, masticator space and jugular foramen. Long term follow up is important because of imprecise nature of the histological criteria for prediction of biologic behavior.We report herein a case of HPC in 66-year-old man, who presented in our department with headache, nasal obstruction and dysphagia. A neck computer tomography scan and magnetic resonance imaging showed a large left parapharyngeal mass bulging into nasopharynx and oropharynx with extension to pharyngeal mucosal surface and causing narrowing of airways and total obstruction of left posterior nostril. Angiography showed a highly vascular neoplasm. Initially he was managed as a case of schwannoma and embolization was done but with no response. An attempt to do complete surgical resection was made, but due to its critical position, it was not possible. During surgery, highly vascularised tumor was found. The histopathologic examination revealed a vascular tumor consistent with hemangiopericytoma G-II. The patient had normal postoperative course of healing and was given adjuvant radiation. He is on regular follow up without signs of recurrence or metastases.In summary, parapharyngeal space is a rare site of presentation for hemangiopericytoma which is highly vascular tumor, requiring extensive work up including magnetic resonance imaging, computed tomography scan and angiography. Complete surgical excision should be attempted. Postoperative radiation is indicated in cases of incomplete resection.