Ultrastructural comparison of capillary and cavernous hemangiomas of the orbit
T. Iwamoto and F. A. Jakobiec
Capillary and cavernous hemangiomas are often grouped together as if they
were modulations of the same entity. To clarify this nosologic question,
three capillary hemangiomas in children and four cavernous hemangiomas in
adults were studied by transmission electron microscopy. The capillary
hemangiomas consisted of two variably admixed zones, solid cellular zones
and zones with open vascular lumens. However, both zones had similar
organization. Each vascular unit was composed of endothelial cells and
pericytes, which persisted in a tumor three years after its clinical
appearance. Macrophages and degenerating cells were found in the
interstitium and may be related to the clinical feature of partial
spontaneous regression. The cavernous hemangiomas had much larger lumens,
and wider and more heavily collagenized trabeculae. The vascular walls were
created by multilaminar smooth muscle cells. Therefore, capillary
hemangioma is completely different from cavernous hemangioma, which
resembles a venous tumor.
