Hemangiopericytoma/Solitary fibrous tumor of the oral cavity.

Hemangiopericytoma/solitary fibrous tumor is a very rare tumor of uncertain malignant potential. About 300 such cases have been reported since 1942, when Stout and Murray described these tumors as "vascular tumors arising from Zimmerman's pericytes". Under the World Health Organization (WHO) classification, hemangiopericytomas and solitary fibrous tumors of the soft tissues are regarded as features of the same entity in the soft tissue fascicle. We report the case of a 54-year-old woman who presented with a painless right-side cheek mass of 2 cm maximum diameter. The lesion was completely removed by wide surgical resection. Histologically, the tumour had staghorn-like vasculature and immunohistochemistry for Calponin, CD68 KP1, AE1-AE3, smooth muscle actin and P63, S-100 was negative; that for CD34 was positive. A diagnosis of hemangiopericytoma/solitary fibrous tumor was rendered. The patient had a normal postoperative course of healing, and 24 months later remains asymptomatic, without signs of recurrence or metastasis. Because of the rarity and unpredictable biological behavior of these tumors, long-term follow-up is necessary even after radical resection because recurrence or development of metastasis may be delayed by many years.