Nasopharyngeal Hemangiopericytoma in a Sudanese child: A Literature Review and Case Report
Hemangiopericytoma (HPC) is an unusual vascular tumor derived from pericytes, first described in 1942 by Stout and Murray1,2. These cells can be found surrounding all capillaries and are thought to be immature smooth muscle derived from mesenchyme. Pericytes add structural support to the capillaries and have a contractile capability playing a role in capillary blood flow regulation, modulating both flux and permeability1,3,4. Approximately 1% of all vasoformative neoplasms are HPC, with 15 to 25% presenting in the head and neck4,5. Of those occurring in the head and neck, approximately 50% involve the paranasal sinuses and nasal cavity. Other sites of predilection are the soft tissues of the scalp, face, and neck, parotid gland, orbit and rarely the salivary glands and larynx. There is no gender predilection and the age of incidence is usually between 50 to 70 years in 90% of cases with only 10% occurring in children. Since HPC is derived from capillary pericytes of Zimmerman`s, its theoretical site of origin can be virtually anywhere in the body. Indeed, HPC has been reported in a wide variety of tissues outside the head and neck, most frequently occurring in skeletal muscle and the retroperitoneum4, 6. The site of lesion has a significant bearing on clinical behavior and perhaps on histological character as well.
Keywords: mesenchyme, retroperitoneum, Zimmerman