Becker's nevus in adults and children

A pigmented, hairy birthmark (epidermal nevus) has another name - Becker's nevus, named after the American dermatologist William Becker, who first described this disease in the late 1940s.

Epidemiology

According to some data, the prevalence of this pathology among patients with dermatological diseases ranges from 0.52 to 2%; in 0.5% of cases these are male patients under 25 years of age. [ 1 ]

The ratio between men and women is approximately 1:1, according to other sources – 5:1.

Causes Becker's nevus

Experts consider Becker's nevus to be one of the sporadic and rare types of epidermal melanocytic nevus, that is, a pigmented formation on the skin. It is also defined as neviform melanosis or Becker's pigmented hamartoma. [ 2 ]

The specific causes of this pathology are currently unknown.

Becker's nevus can develop in a child or teenager, some children are born with this defect. And it may be associated with an abnormality in a gene that has not yet been identified. [ 3 ] Often associated with other congenital diseases [ 4 ], [ 5 ], [ 6 ], [ 7 ]

The formation of epidermal melanocytic nevus occurs due to increased proliferation of epidermal cells, melanocytes and hair follicles. However, no one can yet explain exactly how this happens.

Since the enlargement and darkening of a birthmark with increased hair growth on its surface is observed in adolescence (with the onset of puberty), it is assumed that male sex hormones (androgens) circulating in the blood are involved in their occurrence. [ 8 ]

Risk factors

Without knowing the exact origin, dermatologists have not established the risk factors for the appearance of this type of nevus. But many believe that the main factor is hereditary. Although, according to the results of a few studies, familial cases account for 0.52-2% of all patients diagnosed with neviform melanosis.

Geneticists emphasize the possibility of the existence of heterozygous individuals in several generations with the manifestation of pathology, provided that a clone of homozygous cells is formed as a result of a long-term somatic mutation.

Pathogenesis

The pathogenesis of Becker's melanosis, which is included in the category of congenital melanocytic nevi, is also unclear. As already mentioned, there may be a hormone-dependent nature of the pigment anomaly, which is possibly associated with a local increase in the expression of androgen receptors in the skin.

And the classification of Becker's nevus as a type of skin hyperpigmentation makes it possible to consider its connection with a disruption in the synthesis of the skin pigment melanin by dendritic cells (melanocytes) of the basal layer of the epidermis.

Symptoms Becker's nevus

At birth or later, the first signs of Becker's nevus appear as a clearly defined light brown birthmark on the skin of the upper body - on the shoulders, chest or back, occasionally in other places, but only on one side. No other symptoms are observed.

With age, the spot becomes darker, showing progressive hyperpigmentation, and the skin within its borders becomes thicker. In addition, a lot of hair grows on the spot (this is called hypertrichosis). Sometimes acne appears on the affected area of skin.

Usually only the skin is affected, but there may be congenital accompanying ipsilateral anomalies, i.e. on the same side as the nevus. In such cases, we are talking about the so-called Becker nevus syndrome.

Becker's nevus syndrome may manifest itself as: [ 9 ], [ 10 ]

• hamartoma (proliferation) of smooth muscle tissue;
• hypoplasia (underdevelopment) of the mammary gland or aplasia of the pectoral muscle;
• the presence of an extra nipple;
• hyperplasia of adipose tissue outside the mammary gland;
• hypoplasia of the scapula, shoulder or arm;
• hemivertebra (congenital curvature of the spine);
• protrusion of the sternum and ribs (also called pigeon chest0;
• dystrophy of subcutaneous adipose tissue;
• enlargement of the adrenal glands.

Complications and consequences

Becker's nevus is a benign formation; remote consequences in the form of malignancy of the birthmark have been recorded in medical sources only in a few patients. [ 11 ]

Musculoskeletal and other anomalies are associated with congenital Becker nevus syndrome.

Diagnostics Becker's nevus

As a rule, diagnosis is limited to clinical examination of the affected area of the koi using dermatoscopy.

For more details see – Diagnosis of moles

If the doctor has doubts about the benign nature of a birthmark, a biopsy and histological examination of the tissue sample is performed.

Differential diagnosis

Differential diagnosis includes postinflammatory hyperpigmentation, congenital smooth muscle hamartoma, genetically determined McCune-Albright syndrome, and such a congenital anomaly as giant melanocytic nevus.[ 12 ]

Treatment Becker's nevus

Currently, effective treatment of most cases of Becker's nevus is not possible, and medical care tactics are developed for each specific patient on an individual basis.

Since Becker's nevus creates cosmetic problems that reduce the quality of life of patients, cosmetic surgical treatment can be performed: nevus removal with a ruby laser or fractional resurfacing with a neodymium laser. [ 13 ], [ 14 ], [ 15 ], [ 16 ] However, the effectiveness of such treatment is offset by the high rate of relapses.

It is much easier and safer to remove hair growing on a nevus, for example, using external hair removal products. A case of treatment with the antitumor drug Flutamide has been described. [ 17 ] And to prevent birthmarks from darkening even more, they need to be protected from direct sunlight.

Prevention

There are no preventive measures for this pathology.

Forecast

Unfortunately, there are no pills or ointments for Becker's nevus, and it does not go away on its own. So the prognosis is not very encouraging.