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Facts about the skin from DermNet New Zealand Trust. Topic index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z



Epidermal naevus syndromes

What are epidermal naevus syndromes?

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 an epidermal naevus with other abnormalities in the skin and other organs. They are sometimes called systemitised epidermal naevi. They reflect mosaicism, in which there are two distinct cell lines with differing genetics.

Epidermal naevus syndromes usually arise sporadically, with rare reports of familial cases. Some of the syndromes are now well defined. The molecular / genetic basis is under investigation.

Syndromes associated with sebaceous naevus

Naevus sebaceous or organoid naevus is a type of epidermal naevus in which there is overgrowth of sebaceous glands and/or hair follicles. It is a component of several syndromes.

Sebaceous naevus
Sebaceous naevus

Schimmelpenning syndrome

Schimmelpenning syndrome has two Online Mendelian in Man entries (OMIM 163200, 601359). Its other names include:

Features include:

Phacomatosis pigmentokeratotica

Phacomatosis pigmentokeratotica is an example of didymosis (twin spotting) because two distinct syndromes appear to overlap in one person. It is characterised by:

Naevus spilus is a type of congenital melanocytic naevus. In young babies a flat brown café au lait macule is seen which then develops darker speckles and later these become papules (bumps).

Problems associated with phacomatosis pigmentokeratotica include features associated with Schimmelpenning syndrome (above) and with papular naevus spilus syndrome. These are:

Many other abnormalities have been described in individual cases.

Didymosis aplasticosebacea

Didymosis aplasticosebacea is the association of sebaceous naevus with aplasia cutis congenita.

SCALP syndrome

SCALP syndrome is didymosis aplasticosebacea in association with a giant melanocytic naevus: Sebaceous naevus, Central nervous system abnormalities, Aplasia cutis, Limbal dermoid and Pigmented naevus.

Syndrome associated with comedone naevus

The comedone naevus is composed of a group of blocked hair follicles i.e. blackheads. They are often pitted. It has sometimes been reported in association with other defects.

Various other features have been described in individual cases.

Comedo naevus
Comedone naevus

Syndromes associated with excessive hair growth

These are the angora hair naevus syndrome and Becker naevus syndrome.

Angora hair naevus syndrome

The Angora hair naevus is an epidermal naevus covered with long soft white hair. The syndrome may also include:

Becker naevus syndrome

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:

Becker naevus
Becker naevus

Syndromes associated with keratinocytic epidermal naevi

These include Proteus syndrome, Type 2 segmental Cowden disease and CHILD syndrome.

epidermal naevus
Systemitised epidermal naevus
Keratinocytic epidermal naevus

Proteus syndrome

Proteus syndrome is characterised by overgrowth of skin, connective tissue, fat, bones and other tissues.

Type 2 segmental Cowden disease

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. The PTEN gene's normal function is to suppress tumours. The features of Type 2 segmental Cowden disease include:

CHILD syndrome

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. Pathology characteristically shows foamy histiocytes in the dermal papillae. CHILD naevus can spontaneous disappear only to reappear later.

Other features may include:

Other epidermal naevus syndromes

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:

Related information

References:

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Author: Clin Assoc Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand.

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