Vascular tumors

Abstract

Vascular tumors and malformations of the orbit comprise an important group of orbital space-occupying lesions. Reviews indicate that vascular lesions account for 6.2–12.0 % of all histopathologically documented orbital space-occupying lesions (Table 14.1) [1–5]. There is ultrastructural and immunohistochemical evidence that capillary and cavernous hemangiomas, lymphangioma, and other vascular lesions are of different nosologic origins, yet in many patients these entities coexist. Hence, some prefer to use a single umbrella term, “vascular hamartomatous lesions” to identify these masses, with the qualification that, in a given case, one tissue element may predominate [6]. For example, an “infantile hemangioma” may contain a few caverns or intertwined abnormal blood vessels, but its predominating component is usually capillary hemangioma. This nomenclature does not cover all bases either; it should be noted that although many vascular lesions are made of multiple histopathologic types, all are not. For instance, although caverns lined by endothelial cells are seen in many vascular lesions, no other tissue element is encountered with the classic intraconal “cavernous hemangioma.” In this chapter, the time-honored terminology is used to review cavernous hemangioma, capillary hemangioma, lymphangioma, orbital varix, hemangiopericytoma, angiosarcoma, intravascular papillary endothelial hyperplasia (IPEH), arteriovenous fistulas (AVFs), vascular leiomyoma, angiolymphoid hyperplasia with eosinophilia (ALHE), and Kimura disease.