Rare Primary Care News

Disease Profile

Becker nevus syndrome

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset

All ages





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Hairy epidermal nevus syndrome


Congenital and Genetic Diseases; Female Reproductive Diseases; Rare Cancers;


Becker nevus syndrome is characterized by the presence of a Becker nevus in association with underdevelopment (hypoplasia) of the breast or other skin-related, muscular, or skeletal defects, all of which usually involve the same side of the body as the nevus (ipsilateral).[1] Specific signs and symptoms in addition to the nevus may include ipsilateral breast hypoplasia; skeletal abnormalities such as hypoplasia of the shoulder girdle, scoliosis, fused ribs, and ipsilateral shortness of the arm; and several other features.[2][1] The condition is thought to be sporadic (occurring in individuals with no history of the condition in the family).[1] Treatment varies depending upon the specific symptoms present and the extent of the condition in the affected individual.[2]


Becker nevus syndrome is characterized by the presence of a Becker nevus in association with underdevelopment (hypoplasia) of the breast and/or other skin-related (cutaneous), muscular, or skeletal defects, all of which usually involve the same side of the body as the nevus (ipsilateral).[1] Breast hypoplasia affects both males and females, but is more noticeable in females.[2]

Other muscular and skeletal abnormalities may include:[2][1]

  • Absence of the pectoralis major muscle (pectoral)
  • Underdevelopment of the muscles of the shoulder girdle
  • Abnormal curvature of the spine (scoliosis)
  • Vertebral defects
  • Fused ribs
  • Ipsilateral shortness of a limb
  • Underdevelopment of the teeth and jaws
  • A "sunken chest" (pectus excavatum) or abnormally prominent chest (pectus carinatum)
  • Extra (supernumerary) nipples
  • Abnormally sparse hair under the armpit.

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Hypermelanotic macule
Hyperpigmented spots
Loss of fat tissue in localized area
Smaller or shorter than typical limbs
Shoulder girdle muscle atrophy
Shoulder girdle muscle wasting
Shoulder-girdle muscle atrophy

[ more ]

Supernumerary nipple
Accessory nipple
30%-79% of people have these symptoms
Aplasia/Hypoplasia of the breasts
Absent/small breasts
Absent/underdeveloped breasts

[ more ]

Pectus carinatum
Pigeon chest
Pectus excavatum
Funnel chest
5%-29% of people have these symptoms
Abnormality of the scrotum
Abnormality of tibia morphology
Abnormality of the shankbone
Abnormality of the shinbone

[ more ]

Hypoplastic labia minora
Underdeveloped inner lips
Hunched back
Round back

[ more ]

Lower limb asymmetry
Left and right leg differ in length or width
Rib fusion
Fused ribs
Spina bifida occulta
Supernumerary ribs
Extra ribs
Upper limb asymmetry
Unequal size of arms
Percent of people who have these symptoms is not available through HPO
Cervical ribs
Missing part of vertebrae
Unilateral breast hypoplasia
One underdeveloped breast


Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

    Learn more

    These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

    Where to Start

    • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

      In-Depth Information

      • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
      • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
      • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
      • PubMed is a searchable database of medical literature and lists journal articles that discuss Becker nevus syndrome. Click on the link to view a sample search on this topic.


        1. Wilson H. Y. Lo. Becker Nevus Syndrome. OMIM. May 4, 2000; https://omim.org/entry/604919.
        2. Epidermal Nevus Syndromes. NORD. June 20, 2011; https://www.rarediseases.org/rare-disease-information/rare-diseases/byID/862/viewAbstract.

        Rare Primary Care News