A Review of Proliferative Vascular Disorders of the Central Nervous System of Animals

In disease, blood vessel proliferation has many salient roles including in inflammation, when granulation tissue fills superficial defects, or in the recanalization of an occluded blood vessel. Sometimes angiogenesis goes awry—granulation can be exuberant, and plexiform proliferation of vascular components can contribute to pulmonary hypertension. This review focuses on the diverse manifestations of pathologic vascular overgrowth that occur in the brain, spinal cord, and meninges of animals from birth until old age. Entities discussed include systemic reactive angioendotheliomatosis in which glomeruloid vascular proliferations are encountered in various organs including the central nervous system (CNS). The triad of CNS vascular malformations, hamartomas, and benign vascular proliferations are an especially fraught category in which terminology overlap and the microscopic similarity of various disorders makes diagnostic classification incredibly challenging. Pathologists commonly take refuge in “CNS vascular hamartoma” despite the lack of any unique histopathologic features and we recommend that this diagnostic category be abandoned. Malformative lesions that are often confusing and have similar features; the conditions include arteriovenous malformation, cavernous angioma, venous angioma, and capillary telangiectases. Meningioangiomatosis, a benign meningovascular proliferation with dual components, is a unique entity seen most commonly in young dogs. Last, accepted neoplastic conditions range from lower-grade locally acquired growths like hemangioblastoma (a tumor of mysterious interstitial stromal cells encountered in the setting of abundant capillary vasculature proliferation), the rare hemangioendothelioma, and the highly malignant and invariably multifocal metastatic hemangiosarcoma. Additionally, this review draws on the comparative medical literature for further insights into this problematic topic in pathology.

Case Report of Reactive Angioendotheliomatosis

Reactive angioendotheliomatosis (RAE) is a rare, typically self-limiting, angioproliferative disease that is commonly seen in patients with a variety of inflammatory and systemic diseases. RAE can clinically present as ulcerated, single or multifocal, violaceous papules or plaques. We report a case of a 59-year-old male with a complicated cardiac history who presented with biopsy-proven RAE on the thigh. The differential diagnosis of RAE can include Kaposi sarcoma and angiosarcoma, as well as other non-malignant cutaneous disease. These diagnoses must be excluded before correctly diagnosing and treating RAE. We review the common presentation of RAE along with criteria to exclude other possible diagnoses that can resemble RAE.

Resolution of reactive angioendotheliomatosis in an arteriovenous fistula with innominate vein angioplasty

Introduction: Arteriovenous fistulae (AVF)-associated reactive angioendotheliomatosis (RAE) is a very rare entity (three previously reported cases in the literature) that can manifest as extremity wounds. RAE’s etiopathology is unknown. Case description: We report a case of severe limb-threatening upper extremity wound with pathology-proven RAE. This lesion was previously refractory to standard wound care. There was no evidence of limb ischemia or steal syndrome, previously deemed to be the underlying cause of AVF-associated RAE in other reports. Conclusions: Successful endovascular treatment of an ipsilateral innominate vein stenosis led to reduction of venous hypertension, resolution of associated arm edema, and subsequent wound healing. We therefore propose that venous engorgement and hypertension from central venous stenosis is the likely underlying cause for AVF-associated RAE. If this rare entity is encountered in the setting of AVF, there is utility in treating the wound as a sentinel lesion and venography should be conducted to rule out central venous pathology. Vascular intervention complements aggressive local wound management and biopsy is requisite for prompt diagnosis.