الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
Vascular tumors are relatively rare compared with other neoplasms, However they are diverse and morphologically complex group of lesions that can cause diagnostic difficulty, even for those with years of experience. To further complicate the issue, the categorization of vascular tumors has continued to evolve over time. Some tumors, that were once considered to be high-grade, have recently been reclassified as low-grade malignant (borderline) lesions; others that were previously thought to be in the borderline category are now considered benign. Vascular tumors occur in every organ; the common sites are the skin, nervous system and connective tissue Vascular tumors are divided into benign, intermediate and malignant neoplasms depending on endothelial cell proliferation and clinical characteristics Benign vascular tumors, hemangiomas, are the most common subtype and are often found at birth. Most hemangiomas are superficial lesions with a predilection to the head and neck region. They may also develop internally, including the nervous system and the liver. Intermediate vascular malignancies can recur locally and have some ability to metastasize. Malignant vascular tumors can occur at any location in the body and they may be aggressive tumors with a poor prognosis. Malignant tumors arising at different sites have distinct features.