Neurofibromatosis

70 Neurofibromatosis



Instruction


Examine this patient.



Salient features



History




• Presents in childhood with cutaneous features including café-au-lait spots, axillary freckles and neurofibromas


• Obtain history of learning disabilities (about half the patients with neurofibroma 1 are affected; Nature 2000;403:846–7)


• Childhood leukaemia: the risk of malignant myeloid disorders, particularly juvenile myelomonocytic leukaemia and the monosomy 7 syndrome (a childhood variant of myeloid dysplasia) is 200 to 500 times the normal risk (N Engl J Med 1997;336:1713–20).



Examination




• Multiple neurofibroma and café-au-lait spots (brown macules, >2.5 cm diameter and >5 lesions)


• Examine the axilla for freckles


• Check visual acuity and fundus for optic glioma (Fig. 70.1)


• Hearing and corneal sensation for acoustic neuroma


• The iris for Lisch nodules (often apparent only by slit-lamp examination). The incidence of Lisch nodules in type 1 increases with age (at the age of 5 years only 22% have Lisch nodules, whereas at the age of 20 years 100% have them). Therefore, older individuals who do not have Lisch nodules are unlikely to have type 1 neurofibromatosis (Fig. 70.2)


• The spine for kyphoscoliosis


• Tell the examiner that you would like to check the BP (for renal artery stenosis or phaeochromocytoma).


image

Fig. 70.1 Typical combined hamartoma of retina. Note typical juxtapapillary and epipapillary location of lesion.


(With permission from Yanoff, Duker 2008.)


image image

Fig. 70.2 Neurofibromatosis type 1. Slit-lamp examination (B) is essential for differentiation of Lisch nodules (iris hamartoma) from iris freckles. Iris freckles are flat and have a lace-work structure; Lisch nodules are raised, round, fluffy, and light brown.


(Courtesy Lucian Szmyd, with permission from Habif 2009.)


Remember the triad for neurofibromatosis—neurofibroma, café-au-lait spots and Lisch nodules—allows identification of virtually all patients with neurofibromatosis type 1.



Diagnosis


This patient has multiple café-au-lait spots and neurofibromas (lesion) caused by von Recklinghausen’s disease (aetiology), which are cosmetically disfiguring (functional status).



Advanced-level questions




What are the criteria for neurofibromatosis type 1 (von Recklinghausen’s disease)?


Neurofibromatosis type 1 may be diagnosed when two or more of the following are present:



• Six or more café-au-lait spots, the greatest diameter of which is >5 mm in prepubertal patients and >15 mm in postpubertal patients


• Two or more neurofibromas or one plexiform neurofibroma. Plexiform neurofibroma is considered by some to be a defining lesion of neurofibroma type 1


• Freckling in the axilla or inguinal region (Crowe’s sign)


• Optic glioma


• Two or more Lisch nodules (iris hamartoma)


• A distinctive osseous lesion such as sphenoid dysplasia or thinning of long bone cortex with or without pseudoarthroses


• A parent, sibling or child with neurofibromatosis according to the above criteria.

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Dec 4, 2016 | Posted by in GENERAL & FAMILY MEDICINE | Comments Off on Neurofibromatosis

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