Congenital hemangiopericytoma.

The clinicopathologic features of a case of congenital hemangiopericytoma are described and compared with those of previously reported cases. Features connotative of malignancy in adult or childhood hemangiopericytomas, such as high mitotic activity, increased cellularity, and tissue necrosis or hemorrhage, are frequently observed in congenital tumors. However, the congenital tumors are biologically benign. Spontaneous tumor regression observed in our case further suggests a conservative approach in the treatment of congenital hemangiopericytomas.