Becker Nevus Syndrome

Becker nevus syndrome, or hairy epidermal nevus syndrome, was first described by Happle in 1949, as an association of Becker nevus with breast hypoplasia on one side of the body, and ipsilateral defects of the skin, muscle and skeletal system. In a few cases, they may be bilateral. Many cases of the syndrome go undetected because the clinical features are very mild.

It occurs in both sexes alike, but may be more obvious in women because of the breast involvement.

Androgen receptors in certain parts of the skin are increased in this syndrome. Androgen influences the formation of hair growth as well as muscle and bone development - for this reason, Becker nevus syndrome is thought to be androgen-dependent. It is more commonly found active during puberty, with hyperpigmentation of the nevus and the hair. Increased androgen receptors in the breast could oppose the normal estrogen effect on mammary cells, leading to hypoplasia. The use of spironolactone, which has anti-androgenic effects in the human body, has been found to improve the breast size in one such patient.

Clinical Features

Becker's nevus syndrome may include physical features such as:

• Becker nevus
• Ipsilateral breast hypoplasia
• Musculo-skeletal defects

Becker Nevus

A Becker nevus usually develops around puberty, usually on the upper part of the trunk, although it is sometimes present at birth. The color of the nevus is light brown initially, but at puberty, in response to androgen release and activity, it becomes larger and darker, with increased growth of hair.

Defects of Skeletal and Muscular Development

• Ipsilateral shoulder and/or arm hypoplasia
• Occult spina bifida
• Scoliosis
• Hemivertebra or additional vertebra
• Spinal fusion
• Pectus carinatum or excavatum
• Bilateral stress fractures of the tibia
• Spinal disc herniation
• Asymmetric scapulae

Other Features

• Adrenal hyperplasia
• Temporal region skin hypoplasia
• Lipodystrophy in one or a few areas
• Umbilical hernia
• Sparse axillary hair

In most cases, Becker nevus syndrome is of sporadic occurrence. It is suggested that heterozygotic individuals exist in many generations, without the syndrome being manifested. It is only when a somatic mutation occurs to create a clone of homozygotic cells that the individual develops the condition.

Diagnosis and Treatment

Becker nevus syndrome is diagnosed on the basis of the clinical features and androgen receptor assay. Any individual with a Becker nevus requires evaluation for any associated anomalies of the muscular or skeletal systems.

Becker nevus syndrome is treated by cosmetic surgery if the Becker nevus is creating cosmetic problems because of hypertrichosis and hyperpigmentation.  Removal of the nevus involves laser surgery with the Q-switched ruby laser. Removal of offending hair in the hypertrichotic lesion may be done using laser or electrolysis. Q-switched Nd-YAG laser therapy or fractional resurfacing may also be performed for hyperpigmentation. With all modes of therapy, there is a high recurrence rate.

References

• http://www.scielo.br/pdf/abd/v85n3/en_a15v85n3.pdf
• https://rarediseases.info.nih.gov/diseases/5901/beckers-nevus
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4103296/
• https://rarediseases.info.nih.gov/diseases/3856/becker-nevus-syndrome