ISVD-3 Characterization of cutaneous angiomatosis in dogs and cats

Angiomatosis, a heterogeneous group of potentially progressive, non-neoplastic, possibly congenital vascular proliferations, has not been well documented in dogs and cats. The pathogenesis of angiomatosis is largely unknown. The lesions can be categorized as progressive angiomatosis (PA), scrotal-type vascular hamartoma (STVH), or angiomatosis secondary to lymphedema (ASL). Spontaneous regression has not been seen. Irregular, red to blue macules, patches, nodules and plaques may partially blanch with diascopy. Periodic hemorrhaging may occur. Progressive angiomatosis may develop at any age and most often affects the extremities, but may occur elsewhere. Breed or sex predilections are not known. Canine STVH affects middle-aged or older dogs and develops on the scrotum, tail or caudal trunk. Breeds with pigmented scrotal skin are predisposed. Angiomatosis secondary to lymphedema is a rare condition affecting extremities. Progressive angiomatosis is characterized by interconnected foci of dermal and subcutaneous blood-filled vascular structures of variable size, separated by normal or myxomatous mesenchymal tissue. The vascular channels may have large lumens or resemble capillaries and are lined by mature or slightly enlarged endothelial cells. Thrombosis and intraluminal papillary endothelial hyperplasia may be present. Variable amounts of smooth muscle and fibrous tissue indicate the presence of arterioles and veins. With STVH, clusters are composed of central larger vessels surrounded by capillary buds. With ASL, there is marked lymphedema, primary hypoplasia of the deep lymphatics, and prominent secondary vascular proliferation. Most forms of canine and feline angiomatoses are newly recognized syndromes; as more cases are gathered and documented, nomenclature and classification may change. Funding: Self-funded.