The cell of origin of the hemangiopericytoma is generally accepted as being a mesenchymal, perithelial cell described by Zimmermann1 as the capillary pericyte. He interpreted this cell as being a modified smooth muscle cell, lacking myofibrils. From this derivation, Stout and Murray2 chose the term hemangiopericytoma.
Morphologic variations in tissue culture growths have made exact identification of the tumor cell type impossible.* However, Murray and Stout5 have grown characteristic cells from glomus tumors which they feel are identical with the pericytes of Zimmermann.
The primary tumors tend to be relatively large. In 11 of the cases reported by Stout3 in 1949 the mass exceeded 8.0 cm. in diameter. In the 14 cases of McCormack and Gallivan,6 the size varied from 5 to 13 cm. in the greatest diameter.
Except in very few, in which the tumor has been in the
COLE HN, REAGAN JW, LUND HZ. Hemangiopericytoma. AMA Arch Derm. 1955;72(4):328–334. doi:10.1001/archderm.1955.03730340026005