Author: Hon Assoc Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand, 2010.
An epidermal naevus is a type of birthmark in which there is an overgrowth of one or more components of the epidermis or outer layer of skin. Epidermal naevus syndromes refer to the co-existence of a keratinocytic epidermal naevus or an organoid naevus with other abnormalities in the skin and other organs. They are sometimes called systematised epidermal naevi. They reflect mosaicism, in which there are two distinct cell lines with different genetics and are due to postzygotic mutation.
The epidermal naevus syndromes usually arise sporadically, with the exception of CHILD syndrome, which is familial.
Several authors have commented that the term 'epidermal naevus syndrome' is outdated now that the genetic causes are known for many of the disorders.
Three syndromes associated with a keratinocytic epidermal naevus are now well defined.
CHILD syndrome is inherited as an X-linked dominant disorder and is lethal in males. CHILD stands for Congenital Hypoplasia with Ichthyosiform naevus and Limb defects. It is due to mutations in the gene known as NSDHL (or NAD[P]H steroid dehydrogenase-like gene). This gene involved in the metabolism of cholesterol.
The CHILD naevus is variable, inflamed and covered by waxy yellowish scales. It is usually either strictly on one side of the body (most often the right) with clear-cut midline demarcation, or it may follow Blaschko lines or both. It often favours a body fold. The pathology characteristically shows foamy histiocytes in the dermal papillae. CHILD naevus can spontaneous disappear only to reappear later.
Other features may include:
Multiple hamartoma syndrome or Cowden disease can include a Cowden naevus when it is called Type 2 segmental Cowden disease. The Cowden naevus is a linear, thick, bumpy, wart-like growth. PTEN (phosphatase and tensin homologue) gene mutations have been detected, which are not present in Proteus syndrome, which type 2 segmental Cowden syndrome may resemble (see below). The PTEN gene's normal function is to suppress tumours. The features of Type 2 segmental Cowden disease include:
Fibroblast growth factor receptor 3 (FGFR3) epidermal naevus syndrome (García-Hafner-Happle syndrome) is caused by a mosaic R248C mutation of the FGFR3 Gene.
Schimmelpenning syndrome has two Online Mendelian in Man entries (OMIM 163200, 601359). Its other names include:
Phakomatosis (sometimes spelt phacomatosis) pigmentokeratotica is an example of didymosis (twin spotting) because two distinct syndromes appear to overlap in one person. It is characterised by:
Phakomatosis pigmentokeratotica may include features associated with Schimmelpenning syndrome (above) and with papular naevus spilus syndrome. These are:
Many other abnormalities have been described in individual cases.
SCALP syndrome is didymosis aplasticosebacea in association with a giant melanocytic naevus. The name is an acronym for Sebaceous naevus, Central nervous system abnormalities, Aplasia cutis, Limbal dermoid, and Pigmented naevus.
The comedo naevus is composed of a group of open comedones plugged with keratin and may arise on the head, trunk or limbs. The comedo naevus has sometimes been reported in association with other defects:
Various other features have been described in individual cases.
The Angora hair naevus is an epidermal naevus covered with long soft white hair. The Angora hair naevus or Schauder syndrome may also include:
The Becker naevus presents as darkened skin patches, often with a map-like or checkerboard outline. It is most commonly found on the upper back or shoulders. It tends to be more prominent in males because of the growth of dark hair within it at puberty. The syndrome may also include:
There are numerous individual case reports or small series of cases that do not fit into the descriptions above. Some of these have been given names:
The epidermal naevus syndromes are diagnosed clinically by a careful history and examination. Supportive investigations in a child with systemic or neurological symptoms may include:
A multidisciplinary approach is often necessary to optimise management of symptoms. There is no cure.
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