Nevoid hypertrichosis is a cutaneous condition characterized by the growth of terminal hairs in a circumscribed area. Nevoid hypertrichosis often presents shortly after birth. The cause of nevoid hypertrichosis is unknown. The diagnosis is made based of clinical and histopathological examination.

Signs and symptoms

Nevoid hypertrichosis is a rare disorder characterized by a confined patch of coarse

terminal hair In humans, terminal hair is a variant of hair that is thick and long such as what grows on the scalp, as compared with vellus hair, colloquially known as peach fuzz, growing elsewhere.Marks, James G; Miller, Jeffery (2006)''Lookingbill and M ...

. It often manifests at or shortly after birth, while it sporadically manifests later in life. The lesion is known to stay stable, and the child's growth is directly correlated with any size rise. Though reports of spontaneous resolution are rare, it usually persists. It typically manifests as one or more isolated patches. The absence of any underlying pigmentary alteration or other lesions is the traditional unifying characteristic of these lesions. The hair in the lesions is the same color as the hair on the scalp; nevertheless, there have been instances of premature graying of the hair in the patch as well as depigmented hair.

Causes

Whether nevoid hypertrichosis is a genetically determined condition or a deformity of unknown etiology remains unclear. In giant nevoid hypertrichosis, an autosomal dominant pattern of inheritance has been suggested.

Diagnosis

Histopathological analysis and traditional cutaneous appearance serve as the foundation for the diagnosis. Histopathology is usually required to rule out any underlying

nevus Nevus (plural nevi) is a nonspecific medical term for a visible, circumscribed, chronic lesion of the skin or mucosa. The term originates from ''nævus'', which is Latin for "birthmark"; however, a nevus can be either congenital (present at bi ...

, but it typically reveals a normal

epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and Subcutaneous tissue, hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the ...

with an increased number of morphologically normal

hair follicles The hair follicle is an organ found in mammalian skin. It resides in the dermal layer of the skin and is made up of 20 different cell types, each with distinct functions. The hair follicle regulates hair growth via a complex interaction betwe ...

in the dermis. Congenital hairy

melanocytic nevus A melanocytic nevus (also known as nevocytic nevus, nevus-cell nevus and commonly as a mole) is a type of melanocytic tumor that contains nevus cells. Some sources equate the term mole with "melanocytic nevus", but there are also sources that equ ...

, congenital hypertichosis lanuginosa, plexiform neurofibroma, and generalized

hypertrichosis Hypertrichosis is an abnormal amount of hair growth over the body. The two distinct types of hypertrichosis are generalized hypertrichosis, which occurs over the entire body, and localized hypertrichosis, which is restricted to a certain area. ...

are differential diagnoses that need to be ruled out in cases with early onset.

Becker's nevus Becker's nevus (also known as "Becker's melanosis", "Becker's pigmentary hamartoma", "nevoid melanosis", and "pigmented hairy epidermal nevus") is a benign skin disorder predominantly affecting males. The nevus can be present at birth, but more oft ...

, late onset

, and smooth muscle

hamartoma A hamartoma is a mostly benign, local malformation of cells that resembles a neoplasm of local tissue but is usually due to an overgrowth of multiple aberrant cells, with a basis in a systemic genetic condition, rather than a growth descended f ...

should be taken into consideration for patients with a delayed onset.

Treatment

For management, the patient should be counseled about the condition's benign nature, which will relieve their anxieties. The goal of treatment is to improve appearance, particularly if the lesion is on a body part that is visible. Long pulsed neodymium-doped yttrium aluminum garnet and

alexandrite The mineral or gemstone chrysoberyl is an aluminate of beryllium with the formula Be Al2 O4. The name chrysoberyl is derived from the Greek words χρυσός ''chrysos'' and βήρυλλος ''beryllos'', meaning "a gold-white spar". Despit ...

lasers have been tried for laser hair reduction with positive cosmetic results.

References

External links

Hypertrichosis
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DermNet DermNet is a worldwide clinical resource website about dermatology and skin conditions. Its co-founder and former editor-in-chief is dermatologist and Adjunct Associate Professor Amanda Oakley. The website was launched in 1996 under the umbrella ...

{{Disorders of skin appendages Conditions of the skin appendages