Peripheral vascular tumors are rare, yet some physicians encounter patients with these tumors regularly and most physicians encounter them at least several times in the course of their practice. The clinical significance of vascular tumors ranges from trivial to cosmetically and psychosocially burdensome to life threatening. Some have characteristic clinical manifestations while many are found incidentally but have characteristic imaging findings. However, rare lesions and variable clinical presentations can result in delayed or misdiagnosis. This chapter will provide an overview of primary vascular tumors, emphasizing those affecting arteries and capillaries.
Primary vascular neoplasms are defined as those arising from vascular elements, such as endothelial cells and pericytes. Most involve the microvasculature and manifest in the skin, but others affect deep structures and occasionally manifest in large vessels.
Historically, clinicians and pathologists have used conflicting descriptions and schemes in classifying vascular tumors and vascular malformations (VM). In some cases, different labels have been used to describe the same disease while in other cases the same label has been applied to vastly different diseases.
In 1982, Mulliken and Glowacki1 published a classification system based on endothelial characteristics and biologic behavior, in part to address this confusion (Table 50-1). A subsequent revision of their classification system broadened the category of vascular tumors of infancy to include pyogenic granuloma, tufted angioma, kaposiform hemangioendothelioma (KH), and hemangiopericytoma.2 This revised classification has become the standard for distinguishing hemangiomas from VM and is the official classification schema of the International Society for the Study of Vascular Anomalies.
TABLE 50-1.Classification of Primary Vascular Tumors ||Download (.pdf) TABLE 50-1. Classification of Primary Vascular Tumors
Pyogenic granuloma (lobular capillary hemangioma)
Tufted angioma (Angioblastoma of Nakagawa)
Despite the current acceptance of this standard, imprecise terminology remains widespread in the scientific literature.3 Furthermore, pathologists, who are often unaware of a patient's clinical presentation, still use histopathologic diagnoses and classify vascular lesions by the type of vessel that predominates (arterial, venous, or lymphatic). In contrast, clinicians often make the diagnosis without relying on biopsy or histopathology.
Hemangiomas are benign tumors of vascular endothelium and, by far, the most common form of primary vascular tumor. They most commonly affect the skin, but can occur in nearly any organ (Table 50-2). Hemangiomas are often without clinical significance, but they can cause complications such as disfigurement, ulceration, ...