Crystalloid inclusions in endothelial cells of cellular and capillary hemangiomas. A possible sign of cellular immaturity.

The fine structure of crystalloid inclusions were found in the endothelial cells of capillary (strawberry) hemangiomas and cellular hemangiomas in nine infants. The inclusions measured from 0.5 to 2.0 microns in diameter and showed parallel lamellar bands with a regular periodicity of about 180 to 300 A. The presence of crystalloid inclusions and the absence of typical rod-shaped tubulated Weibel-Palade bodies suggest the immaturity and embryonic character of the endothelium present in the blood vessels of these kinds of hemangiomas.