Hemangiomas are extremely common, benign vascular tumors. They are the mostcommon tumor in infants appearing on the skin, mucous membranes, or internal organs. The major types are capillary and cavernous hemangiomas. Hemangiomas may spontaneously regress.
Hemangioblastomas are associated with von Hippel-Lindau disease, which maycause multiple hemangioblastomas involving the cerebellum, brain stem, spinal cord, and retina, as well as renal cell carcinoma.
Glomus tumors (glomangioma) are benign, small, painful tumors of the glomusbody that usually occur under fingernails.
Kaposi sarcoma is a malignant tumor of endothelial cells associated with Kaposi-sar-coma–associated virus (HHV8). The condition causes multiple red-purple patches, plaques, or nodules that may remain confined to the skin or may disseminate. Microscopically, there is a proliferation of spindle-shaped endothelial cells with slit-like vascular spaces and extravasated erythrocytes.
· The classic European form occurs in older men of Eastern European or Medi-terranean origin, who develop red-purple skin plaques on the lower extremities.
· The transplant-associated form occurs in patients on immunosuppression for organ transplants; involves skin and viscera; may regress with reduction of immunosuppression.
· The African form occurs in African children and young men in whom gen-eralized lymphatic spread is common.
· The AIDS-associated form is most common in homosexual male AIDS patients; it is an aggressive form with frequent widespread visceral dissemi-nation. Common sites of involvement include skin, GI tract, lymph nodes, and lungs. This form of Kaposi sarcoma is responsive to chemotherapy and interferon-alpha, and only rarely causes death.
Angiosarcoma (hemangiosarcoma) is a malignant vascular tumor with a high mor-tality that most commonly occurs in skin, breast, liver, and soft tissues. Liver angio-sarcomas are associated with vinyl chloride, arsenic, and thorotrast.