FROSTED BRANCH ANGIITIS: Idiopathic Retinal Vasculitis, Aneurysms, Neuroretinitis, and Acute Multifocal Hemorrhagic Retinal Vasculitis

Abstract

In the diagnosis of a systemic vasculitis, a physician starts with the patient history and examination. Later appropriate laboratory tests are ordered. After these are reviewed, it is common to perform a biopsy and use histopathologic examination to help diagnose and classify the vasculitis. The diagnosis of a retinal vasculitis also starts with a history and examination. With the retinal vasculitides clinicians have the advantage of actually being able to see the inflamed vessel. The vasculitis may involve any or all elements of the vascular circuit, including the arterioles, capillaries, and venules. The proper diagnosis of retinal vasculitis frequently depends on pattern recognition, because many conditions cannot be confirmed by laboratory testing. In addition, biopsy of the intraocular is impractical or overly invasive. The retinal vasculitides are usually split into two large groups: those with a primarily localized ocular problem and those with a systemic disease that may also have retinal vasculitis as a component. On occasion a patient with a systemic disease, such as sarcoidosis or leukemia, may present with a retinal vasculitis as the first sign of disease. Many patients with a retinal vasculitis as part of systemic disease have a known systemic diagnosis on presentation to the ophthalmologist. The remaining patients with retinal vasculitis have a localized ocular problem. Some of these patients will have nonspecific inflammation of retinal vessels. Other patients may have additional signs that may help in classifying the vasculitis. The identification of these differentiating features relies on pattern recognition. This article discusses three entities that are diagnosed primarily by their ophthalmoscopic appearance. For the most part, there are no supportive laboratory tests or biopsies available to help establish or confirm the diagnosis. Some patients present with an incredible sheathing of the retinal vessels, to the extent that the blood column is obsured by a coat of perivasculitis. In 1976 Ito and associates 14 examined a 6-year-old boy who had bilateral uveitis with profound sheathing of the retinal vessels. Based on the opthalmoscopic appearance, and not on the pathophysiology or histopathology, the retinal vasculitis was called frosted branch angiitis. Since then a number of cases have been reported in Japan, the United States, and elsewhere with additional features. In addition, some patients have had frosted branch appearance secondary to an ocular or systemic disease. A classification system of frosted branch angiitis based on clinical course, proposed cause, and treatment is presented.