9 Clinical and Molecular Biology of Angiosarcoma N.J. Andersen 1 , R.E. Froman 1 , B.E. Kitchell 2 and N.S. Duesbery 1 1 Laboratory of Cancer and Developmental Cell Biology, Van Andel Research Institute Grand Rapids, 2 College of Veterinary Medicine, Michigan State University East Lansing, Michigan, USA 1. Introduction ‘Skepticism is a healthy response to diagnosis of any tumor as angiosarcoma. ‘ (Lane, 1952) Angiosarcoma (AS) is an aggressive malignancy of vascular tissue or vessel forming cells (Requena & Sangueza 1998). AS is rare in humans, making up 1-2 % of soft-tissue sarcomas (Young et al. 2010) and having an estimated incidence of 0.2/100,000 persons per year. Although AS can present anywhere in the body, in humans they typically arise in the skin or superficial soft tissues. It is most frequently noted on the face and scalp of elderly men where their persistent growth causes ulceration and infection, as well as on breasts, and extremities (Brennan et al. 2001; Fayette et al. 2007; Glazebrook et al. 2008). Less frequently AS arises in liver, heart, and spleen (Young et al. 2010). The literature is replete with retrospective analyses and case studies on AS but the rarity of patients diagnosed with this disease makes it difficult to perform more than a superficial investigation on the biology and clinical behavior of AS. However, the occurrence of AS is not restricted to humans and there are several alternative animal models with the potential to inform human studies. We have written this review to collect, compare, and contrast diverse reports on the biology and treatment of AS in humans and alternative animal models. Our objective is to establish a comparative framework to focus further discussion and scientific enquiry. 2. Types of AS While there is general agreement angiosarcomas arise from endothelial cells, its causes are uncertain. There appears to be no single cause of AS in humans; rather, a variety of factors have been reported to contribute to risk of disease. Broadly speaking the causes of this disease may be classified as environmental, familial, and iatrogenic. 2.1 Environmental AS Chronic exposure to any of several environmental risk factors has been linked with AS. Each of these directly or indirectly induce genetic mutations and alter gene expression. Vinyl chloride was first identified as an AS inducing compound when it was noticed that industrial plastic and synthetic rubber manufacturers as well as beauty salon personnel had www.intechopen.com