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E1796. A Multisystem Evaluation of Neurofibromatosis 1: Going Beneath the Skin
Authors
  1. Elizabeth Ryals; UT Southwestern Medical Center
  2. Laura Klesse; UT Southwestern Medical Center
  3. Cory Pfeifer; UT Southwestern Medical Center
Background
Neurofibromatosis 1 is an autosomal dominant phakomatosis and tumor predisposition syndrome that involves multiple organ systems. Understanding the disease is an essential educational building block of pediatric radiology and pediatric neuroradiology because of the diverse pathology that it produces, often resulting in neoplasia that requires appropriate surveillance.

Educational Goals / Teaching Points
The diagnostic criteria for Neurofibromatosis 1 are delineated. The distribution and pathological basis for the focal areas of signal intensity in the brain are defined. Common tumor types that manifest are described. Surveillance strategies are suggested with emphasis on imaging.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Neurofibromatosis 1 (NF-1), also known as von Recklinghausen's disease, is caused by a mutation in the neurofibromin gene on the 17th chromosome (17q11.2). While the disorder is inherited in an autosomal fashion, approximately half of all cases develop as a result of a de novo mutation. The disease manifests during childhood and affects males and females equally with a wide range of clinical variability, even within families, with dysplasias involving the central and peripheral nervous systems, axial and appendicular skeleton, skin, and blood vessels. Decreased expression of the tumor suppressor neurofibromin results in propensity to develop CNS and extra-CNS tumors. Intracranial abnormalities include focal areas of signal intensity, optic pathway gliomas, other low-grade glial neoplasms, and moyamoya arteriopathy. Sphenoid wing dysplasia, plexiform neurofibromas of the head, neck and orbit, and buphthalmos of the globe can be seen. Spinal manifestations include extradural and/or intradural neurofibromas, kyphoscoliosis, and dural ectasia. Musculoskeletal involvement including long bone bowing deformities, pseudoarthroses, and limb hypertrophy can occur. Neurofibromas can occur in the abdomen and pelvis involving the lumbosacral plexus, gastrointestinal tract, genitourinary system and within solid organs. Renal arteriopathy and stenosis is a common finding. Malignant peripheral nerve sheath tumors arise from peripheral nerve sheath or plexiform neurofibromas in any of the above locations. They are aggressive tumors which may present with pain or be clinically occult. Additionally, patients with NF-1 are more likely to develop a variety of tumors affecting multiple organ systems including pheochromocytomas, gastrointestinal stromal tumors, leukemia, and lymphoma.

Conclusion
NF-1 is the most common neurocutaneous disorder and a common inherited tumor predisposition syndrome. Widely variable phenotypic expression and clinical course for those with NF-1 presents a challenge for clinicians when considering surveillance protocols. As an important part of the multidisciplinary team caring for these patients, pediatric radiologists and neuroradiologists need to be aware of the imaging appearance of multisystem manifestations of NF-1 and knowledgeable about surveillance strategies to guide appropriate management decisions.