Epidermal Naevus Syndromes

See also: Epidermal naevus, sebaceous naevus.

Synonyms: ENS, Schimmelpenning syndrome, Schimmelpenning-Feuerstein-Mims syndrome, Feuerstein-Mims syndrome, Solomon syndrome, linear sebaceous naevus (LSN) syndrome, organoid naevus phakomatosis, Jadassohn naevus phakomatosis.

They are all very uncommon syndromes, without reliable population incidence figures. The estimated prevalence of the dermatological lesions in newborns is a fraction of one percent, and only a minority of these will show features of the epidermal naevus syndrome. In a recent survey about one-third of cases were associated with sebaceous naevus. ILVEN and LNC syndromes are relatively rare, accounting for <10% of cases between them.²

• The epidermal naevus will be noted as a patch or plaque of overgrown abnormal skin, present from birth or shortly thereafter.
• They may be linear lesions that follow Blashcko's lines (purported embryonic lines of ectodermal cleavage).^4,5
• The skin lesions may be widely distributed but are often not so.
• The lesions are usually asymptomatic apart from those of ILVEN where they may be inflamed and irritated.
• Common extra-dermatological manifestations of epidermal naevus syndromes include:
  • Epilepsy
  • Mental retardation
  • Neurological deficits
  • Vitamin-D-resistant rickets
  • Spina bifida
  • Hyperplastic bone growth
  • Ptosis
  • Nystagmus
  • Optic nerve defects
  • Oculomotor dysfunction.

• Uncomplicated dermatological epidermal naevus/sebaceous naevus
• Dermatological naevus with co-incidental cause for eye/CNS/skeletal abnormality
• Von Recklinghausen's neurofibromatosis
• Alternative syndromal presentation of ENS, e.g. Proteus/CHILD syndrome
• Epidermodysplasia verruciformis
• Keratosis follicularis (Darier's Disease).

• Skin lesions should be referred for dermatological assessment and/or biopsied to ascertain their nature.
• Ocular lesions should be examined with a slit lamp by an ophthalmologist.
• CT/MRI are used to assess the presence/degree of any intracerebral lesion.
• Skeletal survey or localised x-rays may be used to determine if there is any skeletal involvement.
• EEG is used to assess patients who are suspected of having epilepsy due to the presence of intracerebral epidermal naevus syndrome; epileptiform foci are usually ipsilateral with any skin lesion.

Several syndromes have been identified that have an epidermal naevus syndrome as part of their features, with other associated abnormalities. They include:

• Proteus syndrome
• Congenital hemidysplasia with ichthyosiform naevus and limb defect (CHILD syndrome)
• Phakomatosis pigmentokeratotica.

• There is little useful therapy available.
• The skin lesions can be excised for cosmetic reasons, but may be too extensive to make this an option.
• Epidermal naevi are usually resistant to treatments such as topical/intralesional steroids, dithranol, topical retinoids and cryoablation.
• Some lesions may respond to topical calcipotriol but this is unlicensed for use in children.²
• If the naevus is extremely warty or chronically inflamed (as in ILVEN syndrome) then topical immunomodulatory agents such as tacrolimus and fluocinonide may be helpful.⁶
• Cataracts and other ocular lesions may be treated by surgical means if felt to be worthwhile from an ophthalmological viewpoint.
• Epilepsy is managed using anti-convulsants as in idiopathic/other secondary epilepsies.
• There is currently no useful therapy available to treat neurological dysfunction associated with the syndrome.

• Neurological dysfunction/mental retardation and epilepsy
• Ocular and oculomotor dysfunction
• Skeletal deformity and/or dysfunction (e.g. spina bifida, vitamin-D-resistant rickets)
• Inflammation and irritation within the skin lesion (ILVEN syndrome)
• Benign or malignant tumours may arise within the lesion, although malignant transformation is thought to be relatively rare.^7,8

• Prognosis for the skin lesion is usually good and malignant transformation relatively rare.
• Prognosis with regards to cerebral/ocular and skeletal dysfunction depends upon the extent of hamartomatous involvement at extra-dermatological sites.