Neurofibromatosis type 1: More than skin deep
Dermatologic findings manifest in childhood, but the disease progresses to multiple organ systems. Here’s how to proceed if you diagnose this in your patient.
Neurofibromas are benign subcutaneous palpable lesions that grow within peripheral nerve tissue, including spinal, subcutaneous, plexiform, or dermal encapsulated nerves. Originating in Schwann cells, they are composed of fibroblasts, mast cells, macrophages, endothelial cells, and other perineural cells. Some patients show disfiguration when hundreds of these masses are present (FIGURE). These tumors increase in number as the patient ages or during pregnancy, which is thought to be secondary to hormonal changes.7 They are sometimes painful and can be pruritic. Their appearance can also cause patient distress.
The diagnosis is a clinical one
Suspicion for NF1 should be high in patients presenting with the dermatologic findings described, although CALMs and freckling are not exclusive to NF1. Diagnostic criteria for NF1, which distinguish it from other conditions, were first outlined in a National Institutes of Health Consensus Development Conference Statement in 1987.8 The list of criteria has subsequently been expanded.
While the presence of at least 2 criteria is required for diagnosis,2 NF1 should be suspected in individuals who have any of the following findings8,9:
- the presence of at least 6 CALMs that are > 5 mm in prepubertal children and > 15 mm in adults
- 2 or more neurofibromas of any type, or at least one plexiform neurofibroma
- axillary or groin freckling
- optic pathway glioma
- 2 or more Lisch nodules (iris hamartomas seen on slit-lamp examination)
- bony dysplasia (sphenoid wing dysplasia, bowing of long bone ± pseudarthrosis)
- first-degree relative with NF1.
What you’ll see as the disease progresses
NF1 can affect a variety of systems, and potential complications of the disease are numerous and varied (see TABLE9). Here is some of what you may see as the patient’s disease progresses to various organ systems:
Learning disabilities and other cognitive and behavioral problems, such as attention-deficit/hyperactivity disorder, may affect up to 70% of children with NF1. Additionally, children with NF1 have visual/spatial problems, impaired visual motor integration, and language deficits.10 The etiology of cognitive impairment in NF1 is unknown.11
Continue to: Hypertension
