Linear and whorled nevoid hypermelanosis

What causes linear and whorled nevoid hypermelanosis?

While the underlying cause of linear and whorled nevoid hypermelanosis (LWNH) is poorly understood, it is thought to result from genetic mosaicism or chimerism. In each of these circumstances, at least two different cells lines (sets of DNA) are present. Mosaicism results from the presence of at least one different cell line due to a genetic change that occurs early in the development of a single embryo. Chimerism results from the joining ("fusion") of two or more genetically distinct cell lines originating from different fertilized eggs. The presence of pigmentation differences along the lines of Blaschko is thought to reflect the pattern of outgrowth of different cell lines that originate from precursors during embryonic development.

Several chromosome abnormalities have been reported in affected individuals. People with LWNH who have an underlying chromosome abnormality are more likely to have symptoms in addition to those that affect the skin.

Last updated on 05-01-20

Is linear and whorled nevoid hypermelanosis inherited?

Linear and whorled nevoid hypermelanosis (LWNH) generally occurs sporadically (by chance, in people with no family history of LWNH). However, very rarely, familial cases of LWNH have been described.

Last updated on 05-01-20

Why isn't there more documentation regarding linear and whorled nevoid hypermelanosis?

While there is not a calculated incidence or prevalence for linear and whorled nevoid hypermelanosis (there is no official method for tracking rare conditions), the condition appears to be very rare given the few case reports that have been described in the medical literature. The condition usually happens as a chance occurence in a family. In total, around 45 cases have been described in the medical literature worldwide. The rare occurance of linear and whorled nevoid hypermelanosis is one reason why data and information regarding the condition is lacking. Rare conditions can present an especially challenging situation. Since some conditions are so rare, there are few cases to learn from, let alone conduct research.

Last updated on 05-01-20

How might linear and whorled nevoid hypermelanosis be treated?

There is very limited information regarding the treatment of linear and whorled nevoid hypermelanosis (LWNH). Chemical peels and 2% hydroquinone (a skin lightening agent) for treatment of hyperpigmentation have been described. Due to the possible association with chromosome abnormalities and other symptoms, people with LWNH should be evaluated for developmental delays, growth delays, skeletal abnormalities, and congenital heart defects.

Last updated on 05-01-20

Where To Start

Linear and whorled nevoid hypermelanosis

MedlinePlus, the National Library of Medicine Web site designed to help you research your health questions, provides information on pigmentation disorders.

Last updated on 04-27-20

Name: American Academy of Dermatology 1445 New York Ave, NW Suite 800
Washington, DC, 20005, United States
Toll Free: 888-462-DERM (3376) Fax : 847-240-1859 Email: https://www.aad.org/Forms/ContactUs/Default.aspx Url: https://www.aad.org/

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