Contrast-enhanced ultrasonography of hepatic metastasis of hemangiopericytoma

Hemangiopericytoma (HPC) was first described by Stout and Murray(1) in 1942. The cellular origin of HPC was thought to come from the pericytes, which are contractile cells surrounding the capillaries and post-capillary venules.(2-4) The tumor was rare and was reported to most frequently affect patients in their fifth and sixth decades of life, with an almost equal distribution in both sexes.(3,4) Because HPC has a high rate of local recurrence and has a potential for metastasis that cannot be predicted by its histopathologic characteristics, the treatment of choice has been wide surgical excision as the initial therapy.(5,6) However, even surgical resection cannot guarantee complete cure of the disease. Metastases were eventually observed in 64.5% of patients considered to have malignant or potentially malignant tumors. Most of the metastases occurred within 3 years after initial treatment but have been reported to occur after as long as 16 years.(4) The lung, skeleton, and liver were the most common metastatic sites.(3,4,6,7) Contrast-enhanced ultrasonography (CEUS) has allowed excellent depiction of lesional vascularity within focal liver masses. Here we report CEUS of metastatic HPC of the liver. To our knowledge, this is the second case of HPC studied with CEUS reported in the literature.