Hepatic Hemangiopericytoma/Solitary Fibrous Tumor: A Review of Our Current Understanding and Case Study

In 2002, the World Health Organization reclassified the soft tissue tumors known as hemangiopericytoma (HPC) as a variant of solitary fibrous tumor (SFT). As this classification system is still debated and has not been universally applied, the following account will provide an updated review of our understanding of those tumors still classified as HPC in the literature with special emphasis on hepatic HPC/SFT. HPC is a soft tissue neoplasm of mesenchymal origin first described by Stout and Murray in 1942. HPC constitutes 1 % of all vascular neoplasms and has been thought to coexist with trauma, prolonged steroid use, and hypertension. Although its presentation may be variable, intrahepatic HPC often presents with the patient's increasing awareness of a painless mass. Marked hypoglycemia may also accompany the neoplasm. Recent evidence suggests that uncontrolled growth may result from a loss of imprinting with overproduction of IGF-II in addition to alternative promoter usage. Diagnostic modalities including imaging, biopsy, and biochemical assays may be used to detect the presence of HPC. As most lesions are benign and slow growing, the prognosis is relatively favorable with 10-year survival between 54 and 70 %. Current mainstays of treatment include hepatic resection when possible especially with the use of adjuvant radiotherapy. Chemotherapeutic approaches have been poorly studied and are generally reserved for inoperable cases. Antiangiogenic compounds such as temozolomide and bevacizumab provide an exciting avenue of treatment. Finally, a case study will be reviewed highlighting diagnosis, treatment, and spectrum nature of hepatic HPC.