The phakomatoses refer to a variety of neurocutaneous syndromes.1 Almost all are multisystem disorders that are embryonal in origin. Neurofibromatosis type 1 and tuberous sclerosis complex are the most common phakomatoses. These disorders are also discussed in Chapter 182.
NEUROFIBROMATOSIS TYPE 1
Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominant disorders in humans, with an estimated incidence of approximately 1 in 3000 live births. It has diverse manifestations in tissues that are primarily, although not exclusively, of neural crest origin. Clinical findings form the basis of the National Institutes of Health Consensus Statement of diagnostic criteria for neurofibromatosis type 1 (Table 578-1).2 The diagnostic criteria are met in an individual if 2 or more of the features listed are present. Clinical, molecular and management aspects of neurofibromatosis 1 are discussed in Chapter 182.
Optic pathway gliomas are the main central nervous system tumor with a marked increased frequency in neurofibromatosis type 1. Because of their growth, it is recommended that all children age 10 years or younger with neurofibromatosis type 1 undergo annual ophthalmologic examinations. When they progress, visual symptoms are produced because the tumors enlarge and put pressure on the optic nerves-chiasm resulting in impaired visual acuity and visual fields. Extension into the hypothalamus can lead to endocrine deficiencies or failure to thrive.
Six or more café au lait macules over 5 mm in greatest diameter in prepubertal individuals and over 15 mm in greatest diameter in postpubertal individuals
Two or more neurofibromas of any type or 1 plexiform neurofibroma
Freckling in the axillary or inguinal regions
Two or more Lisch nodules (iris hamartomas)
A distinctive bone lesion such as sphenoid dysplasia or thinning of long-bone cortex with or without pseudoarthrosis
A first-degree relative (parent, sibling, or offspring) with neurofibromatosis type 1 by the above criteria
Although more than 50% of individuals with neurofibromatosis type 1 will have only cutaneous neurofibromas, café au lait spots, or Lisch nodules, an estimated 30% to 40% will develop 1 or more of the serious complications in their lifetime. The major categories of these complications are malignancy, learning disability, cerebrovascular disease, hypertension, and scoliosis. Because of the diverse and unpredictable complications associated with neurofibromatosis type 1, close multi-disciplinary follow-up is necessary. Patients with neurofibromatosis type 1 should have regular clinical assessment at least yearly, focusing the history and examination on the potential problems for which they are at increased risk. Laboratory tests and imaging studies should be reserved for investigating specific clinical symptoms and signs. Some of the routine follow-up recommended includes yearly clinical assessment with blood pressure monitoring and yearly ophthalmologic examination.
TUBEROUS SCLEROSIS COMPLEX
Tuberous sclerosis complex is an autosomal dominant multisystem disease. It usually presents with seizures, mental retardation, and autism. Tuberous sclerosis complex affects the brain, eye, skin, kidneys, and heart. It is estimated to affect 1 in 6000 to 10,000 newborns. The diagnosis of tuberous sclerosis complex is still based on clinical criteria. To make the definite diagnosis of tuberous sclerosis complex an individual must have 2 major features or 1 major feature plus 2 minor features. (See Tables 578-2 and 578-3 for major and minor features.) The non-neurologic clinical manifestations, molecular aspects and management of tuberous sclerosis complex patients is discussed in Chapter 182.
Subependymal giant-cell astrocytoma
Facial angiofibroma or forehead plaque
Ungual or periungual fibroma (nontraumatic)
Hypomelanotic macules (> 3)
Multiple retinal hamartomas