Neurocutaneous syndromes, or phakomatoses, are disorders characterized by the presence of hamartomas involving different organ systems, such as the skin, eyes, CNS, and viscera. Phakomatoses are inconsistently defined, and there is a lack of consensus about which conditions should be considered neurocutaneous syndromes. Four major disorders have traditionally been designated phakomatoses:
neurofibromatosis type 1 (von Recklinghausen disease, Fig 14-6) and type 2
tuberous sclerosis (Bourneville disease, Fig 14-7)
angiomatosis of the retina and cerebellum (von Hippel–Lindau disease, Fig 14-8)
ataxia-telangiectasia (Louis-Bar syndrome, Fig 14-9)
Figure 14-6 The most common ocular finding in neurofibromatosis type 1 (NF1) is the presence of iris (Lisch) nodules. These are often light colored in a patient with dark irides (A) but may be relatively darker in patients with light irides (B). The diagnosis is often suggested by cutaneous findings, including café-au-lait spots (C) or skin neurofibromas (D).
(Part A courtesy of Mark J. Greenwald, MD; parts B–D courtesy of Steven A. Newman, MD.)
Figure 14-7 Tuberous sclerosis. A, Hamartomatous angiofibromas (previously called adenoma sebaceum) are a hallmark of this syndrome and involve the cheek, particularly in the area of the nasolabial fold. Other classic skin findings include the presence of an ash-leaf spot (B), best observed with ultraviolet light, and subungual lesions (C). D, Ophthalmic findings include the presence of astrocytic hamartomas on funduscopic examination. E, Intracranial hamartomas often line the subependymal surface. They frequently calcify, becoming obvious on computed tomography (CT) scan.
(Parts A, B courtesy of Mark J. Greenwald, MD; parts C, E courtesy of Steven A. Newman, MD; part D reprinted from Kline LB, Foroozan R, eds. Optic Nerve Disorders. 2nd ed. Ophthalmology Monographs 10. New York: Oxford University Press, in cooperation with the American Academy of Ophthalmology; 2007:164.)
Figure 14-8 Fundus photograph of a patient with von Hippel–Lindau disease, showing a characteristic hemangioblastoma of the retina.
(Courtesy of Steven A. Newman, MD.)
Encephalofacial angiomatosis (Sturge-Weber syndrome, Fig 14-10), racemose angioma (Wyburn-Mason syndrome, Fig 14-11), incontinentia pigmenti, and Klippel-Trénaunay-Weber syndrome are among the other conditions sometimes classified as phakomatoses.
These disorders, which are discussed at length in BCSC Section 6, Pediatric Ophthalmology and Strabismus, are characterized by tumors formed from normal tissue elements: hamartomas and choristomas. A hamartoma is composed of elements normally found at the involved site; hamartomas are not true neoplasms, because they are anomalies of tissue formation that lack the capability for limitless proliferation. The glial retinal tumors of tuberous sclerosis are a type of hamartoma. Choristomas are tumor-like growths composed of tissue not normally present at the site of growth. Some phakomatous lesions are neoplasms, but the majority are hamartomas or choristomas.
Figure 14-9 Photograph of the left eye of a child with ataxia-telangiectasia, showing abnormally dilated and tortuous conjunctival vessels.
(Courtesy of Mark J. Greenwald, MD.)
Figure 14-10 Sturge-Weber syndrome. A, This 1-year-old exhibits a port-wine stain involving the V1 and V2 distributions on the right side, a classic finding in this syndrome. These patients often have congenital glaucoma. B, In an infant with congenital glaucoma, the globe may enlarge significantly (buphthalmos). C, MRI scan shows cortical vascular malformations following the gyral pattern (arrow). Diffuse choroidal hemangiomas may also occur, causing increased hyperemia and redness of the choroid. D, Fundus photograph showing choroidal hemangioma and E, the contralateral normal eye.
(Parts A, B courtesy of Steven A. Newman, MD; part C courtesy of Mark J. Greenwald, MD; parts D, E courtesy of James J. Augsburger, MD.)
Figure 14-11 Fundus photograph shows an arteriovenous malformation (racemose angioma) of the retina in a patient with Wyburn-Mason syndrome.
(Courtesy of Mark J. Greenwald, MD.)
Table 14-2 summarizes the important features of the most common phakomatoses.
Ullrich NJ. Neurocutaneous syndromes and brain tumors. J Child Neurol. 2016;31(12): 1399–1411.
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.