Contributor: Gordon K. Klintworth
A capillary hemangioma is a benign non-encapsulated hamartoma composed of thin walled capillaries. It is usually congenital or becomes apparent shortly after birth. The lesion tends to enlarge for several years and then commonly involutes spontaneously before 10 years of age. Some do not change much in size. The skin of eyelids [hemangioma - eyelid] and the orbit [hemangioma - orbit] are often involved. The capillary hemangioma frequently affects the eyelid of children and causes a strawberry colored cutaneous mass [nevus - strawberry ].When the eyelid is affected in infancy amblyopia can result. A capillary hemangioma can originate in many sites including bone [hemangioma - osseous], such as the frontal bone, particularly in adults. The capillary hemangioma is characterized histologically by the presence of a network of closely packed cords of uniform flattened vascular endothelial cells and vascular channels with the dimensions of capillaries. When actively growing the lesion is often extremely cellular and forms a solid mass with absent or sparse vascular channels [hemangioma - infantile]. Despite a rapid growth and an abundance of mitotic figures the cells have a uniform appearance and lack atypia. Although the histologic appearance may be disturbing the lesion is benign, but a misdiagnosis can be made because of concern about malignant potential. The involution of a capillary hemangioma is accompanied by fibroblastic activity in the intervening stroma and an accumulation of macrophages, which are often laden with lipid and hemosiderin. One type of capillary hemangioma is the nevus flammeus, which is a cardinal feature of Sturge-Weber syndrome.