In 1942, Drs. Margaret Murray and Arthur Stout wrote a paper about a solitary, fibrous neoplasm of capillary blood vessels. Unlike other glomus tumors -- soft tissue growths mainly found under the nails -- these tumors presented a diagnostic challenge. The doctors named the growth hemangiopericytoma (HPCs). The tumors can occur anywhere in the body, even in the brain. Because they are rare, many medical questions remain under investigation, but some treatment methods have proven successful.
First described in the 1870s and named in 1923 by K.W. Zimmerman, pericytes are cells on the walls of capillaries. These cells are found in spiraling capillaries and venules and are responsible for vessel formation and blood flow, as well as the maintenance of the blood-brain barrier and regulating the entry of immune cells into the central nervous system. Studies suggest pericytes are the starting point of hemangiopericytomas.
Three membranes or meninges enclose the brain and spinal cord: dura mater, arachnoid, and pia mater. Meningeal hemangiopericytoma is an aggressive dural mass that accounts for less than one percent of intracranial tumors. They generally occur in adults between the ages of 30 and 50, with ten percent of cases diagnosed in children. Between 1938 and 1987, there were 44 cases of meningeal HPC, with 55 percent of them occurring in men.
Symptoms of HPCs of the lungs include but are not limited to shortness of breath with or without a cough. For HPCs near the kidneys, urinary retention, inability to empty the bladder, and hydronephrosis -- swelling of a kidney due to urine build-up -- are key symptoms. Once doctors examine and diagnose the cause, they can explore the available treatment options.
The causes of HPC aren't yet known. What scientists do know is that the growths are generally found in adults and can develop wherever there is endothelial tissue. In the past, three cases of malignant HPC occurred in one family, suggesting autosomal recessive inheritance. Research also suggests occupational exposure to vinyl chloride among plastic industry workers, as well as dioxin-based herbicides, may be responsible for some cases of malignant hemangiopericytoma.
Hemangioma is unusual blood vessel buildup under the skin or in the internal organs. There are two types of hemangiomas: hemangioblastomas and hemangiopericytomas. Hemangioblastomas are benign, slow-growing tumors in the blood vessel lining. They don't invade surrounding tissues, unlike hemangiopericytomas, which start in the cells around the blood vessels and can recur or spread.
When it comes to understanding the severity of hemangiopericytomas, doctors use the World Health Organization's four-step grading system, which classifies HPCs as WHO II or III. Grade II tumors are malignant or benign, relatively slow-growing, and tend to recur as higher grades. Grade III have the same recurrence tendency but are malignant.
Up to 25 percent of all hemangiopericytomas occur in the head and neck region, but only one percent of sinonasal tumors are diagnosed as HPCs; these growths develop in individuals in their sixties and seventies and present as nasal obstructions or nasopharyngeal hemorrhages. They tend to originate in muscle tissue and not around the blood vessel, making them distinctive. This type of tumor is described as lazy and can surgery can successfully remove them in most cases. It is uncommon for them to recur and metastasize.
To treat difficult head and neck hemangiopericytomas such as sinonasal tumors, doctors may choose an endoscopic endonasal approach or EEA, a minimally invasive treatment, to remove the mass. The surgeon inserts an endoscope into the nose and sinus cavities. This tool gives the surgeon an image of the tumor and the area around it so that he can extract the tumor and other affected tissue with precision. The lack of a facial incision in this method reduces recovery time and trauma.
For those with small, benign hemangiopericytomas in the brain, Gamma Knife radiosurgery (GKRS) is a viable non-invasive option. Radiosurgery is an approach that combines neurosurgery radiation and oncology; the doctor delivers targeted radiation to a central nervous system mass in one session, with the help of 192 focused, small beams. Targeting the tumor with GKRS provides accuracy of within one millimeter.
Most hemangiopericytomas are painless, but physicians can use other symptoms to prompt a diagnosis through physical examination as well as MRIs or CT scans. According to researchers, between 25 and 30 percent of HPCs are anaplastic, grade IV. As long as diagnosis and treatment are prompt, more than 90% receive a five-year prognosis. However, these tumors tend to reappear as a higher grade, which reduces the survival rate. Overall, the prognosis for hemangiopericytomas depends on a variety of factors, but diagnosis and treatment improve survival rates.
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