Question: What is (are) Hemangiopericytoma ?
Answer: Hemangiopericytoma is a term used to described a group of tumors that are derived from pericytes, the cells normally arranged along specific types of blood vessels called capillaries and venules. These types of tumors are typically slow-growing, may be either benign (non-cancerous) or malignant (cancerous), and may occur anywhere in the body.
Source: GARD

Question: What causes Hemangiopericytoma ?
Answer: What causes hemangiopericytoma? The cause of the disease is unknown, and no strong clinical data exist to indicate a convincing link to specific causes. Some reports suggest a relationship between hemangiopericytoma and occupational vinyl chloride exposure, as well as exposure to herbicides.
Source: GARD