Hemangiopericytoma
Overview
Hemangiopericytomas are rare vascular tumors that arise from pericytes, which are cells that are associated with capillary walls. These tumors can originate anywhere in the body there are capillaries, which is virtually everywhere. The most common locations reported are the lower extremities, pelvic area, head, and neck. They occur in all ages and equally in both sexes. They can be either benign or malignant, and can metastasize, with the most common sites being the lungs and bones.
Symptoms
These tumors usually present as painless masses, often without any associated symptoms. They can remain undetected for long periods of time, due to the fact that they originate in soft tissue that is flexible and easily makes room for the new mass. Symptoms are likely to be associated with an enlarging mass and vary greatly according to the area of the body where the mass is located. They can mimic meningiomas around the brain and skull base causing neurologic disturbances.
Causes
There is some evidence for a genetic component, as people with certain genetic conditions are more likely to develop this type of tumor. For example, an abnormality of the tumor suppressor gene, as is seen in patients with Li-Fraumeni syndrome, has been linked to an increased risk of soft tissue sarcomas. Genetic mutations caused by exposure to radiation or certain chemicals may also result in the development of soft tissue sarcoma. However, in most cases of hemangiopericytoma, there is no identifiable cause.
Prevention
Currently there are no guidelines for preventing hemangiopericytomas.
Diagnosis
Imaging studies will reveal the exact location and size of the mass, as well as the extent of spread. Biopsy of the tissue allows for the identification of specific characteristics. These tumors are made up of thin walled blood vessels of various sizes and shapes surrounded by uniform, elongated cells. However, there are several types of tumors with a similar appearance, making a positive diagnosis elusive.
Treatment
Surgical removal of the tumor is the primary treatment. The approach used depends upon the location and size of the tumor. Hemangiopericytomas of the skull base can be directly approached through endoscopic endonasal approach (EEA). This state-of-the-art, minimally invasive surgical procedure uses the nose as a natural corridor to reach these lesions. There are no incisions in the skin of the face or head. Surgery may be followed by radiation therapy to prevent recurrence, usually localized to the post operative site and particularly in cases where the tumor was not totally removed. Chemotherapy is also effective for treating hemangiopericytomas and is often prescribed to follow surgery. Both radiation and chemotherapy are recommended for cases where complete removal of the tumor is not possible.