Hemangiopericytomas
Hemangiopericytomas are a type of soft-tissue sarcoma that originate from pericytes, which are cells that surround small blood vessels and capillaries. These tumors typically occur in adults, especially during their fifth or sixth decades of life, although a rare form can affect infants under one year old. The exact cause of hemangiopericytomas remains poorly understood, and no specific risk factors have been conclusively identified, although some associations with environmental exposures and genetic predispositions have been noted in the context of soft-tissue sarcomas.
Clinically, hemangiopericytomas often present as painless soft tissue masses, commonly located in the legs, pelvis, and retroperitoneum, but can also occur in the head and neck. Diagnosis relies on histological examination of tumor samples, as there are currently no screening tests available. Treatment typically involves complete surgical removal of the tumor, with additional radiotherapy or chemotherapy recommended for cases that are not fully resectable. Prognosis can vary; while a reported ten-year survival rate is around 70%, the potential for local recurrence and metastatic spread, particularly to the lungs and bones, makes ongoing monitoring essential.
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Subject Terms
Hemangiopericytomas
ALSO KNOWN AS: Perithelioma, myopericytoma
RELATED CONDITIONS: Soft-tissue sarcomas
DEFINITION: Hemangiopericytomas are soft-tissue sarcomas derived from pericytes (cells of the connective tissue surrounding capillaries and other small blood vessels). Their malignancy is variable and unpredictable, most commonly encountered in adults.
Risk factors: There are no identifiable risk factors particular to hemangiopericytoma, although several risk factors associated with soft-tissue sarcomas have been identified. These include exposure to chlorophenols in wood preservatives and phenoxyacetic acid in herbicides, exposure to ionizing radiation, and rare genetic predispositions in some families.
Etiology and the disease process: Etiology is poorly understood, and connections with diet, smoking, alcohol, or preexisting conditions have not been established.
Incidence: Less than 1 percent of newly diagnosed cancers are soft-tissue sarcomas, and fewer than 5 percent are hemangiopericytomas. They typically arise in the fifth or sixth decade of life. Only 5 to 10 percent of the cases are found in children. A distinct rare infantile form is known in children under twelve months. The overall incidence is estimated at .06 per 100,000 people.
Symptoms: Tumors usually develop as a deep soft-tissue mass, most commonly in the legs, pelvis, and retroperitoneum (back of the abdominal cavity), although one study found 16 to 25 percent of new cases manifest as lesions in the head and neck. Detection is often first noted as a painless swelling of the soft tissue, although growing abdominal tumors may cause painful intestinal or urinary symptoms. An occasional symptom is a pronounced hypoglycemia resulting from tumor secretion of insulin-like growth factors. Other symptoms include low blood sugar, nausea, eye pain, and headache.
Screening and diagnosis: The existence of hemangiopericytoma as a distinct class of sarcomas is controversial because other related neoplasms show a very similar vascular growth pattern. Diagnosis is based on direct histological examination of tumor tissue. No screening tests exist, and hemangiopericytoma is sufficiently rare and unpredictable that uniform staging criteria have yet to be developed.
Treatment and therapy: In adults, complete surgical removal and resection are favored when possible. Radiotherapy and chemotherapy have proven effective, and these are particularly recommended for patients with incomplete resection or large invasive tumors.
Prognosis, prevention, and outcomes:Malignant hemangiopericytoma is prone to local recurrence and metastasis to distant sites, most commonly the lungs and bones. Tumors of the head, neck, and trunk seem far more likely to recur locally than do tumors of the extremities. Metastasis in the lungs and bone marrow and reoccurrence in the pelvis are the most common. One study reported a ten-year survival rate of 70 percent, but local and distant recurrences are known to occur after a prolonged disease-free interval.
Bibliography
Folpe, Andrew L., et al. Bone and Soft Tissue Pathology. 2nd ed., Elsevier, 2023.
Goldblum, John R., et al. Enzinger and Weiss's Soft Tissue Tumors. 7th ed. Elsevier, 2020.
"Hemangiopericytoma." Boston Children's Hospital, www.childrenshospital.org/conditions/hemangiopericytoma. Accessed 20 June 2024.
Klijanienko, Jerzy, and Real Lagace. Soft Tissue Tumors: A Multidisciplinary, Decisional, Diagnostic Approach. Wiley, 2011.
Prayson, Richard A., and Gabrielle A. Yeaney. Neuropathology: A Volume in the Series: Foundations in Diagnostic Pathology. 3rd ed., Elsevier, 2024.
Raghavan, Derek, et al. Textbook of Uncommon Cancer. 5th ed. Wiley, 2017.
Wang, Kewei, et al. “Hemangiopericytoma: Incidence, Treatment, and Prognosis Analysis Based on SEER Database.” BioMed Research International, 2 Nov. 2020, doi:10.1155/2020/2468320.