Pili Annulati

Pili annulati, derived from Latin, meaning “ringed hair,” is a rare hair disorder characterized by alternating light and dark bands on the hair shafts. These bands, which are visible to the naked eye, are caused by changes in the hair’s structure and composition. Pili annulati is a genetic condition inherited in an autosomal dominant pattern, meaning that an affected individual has a 50% chance of passing the condition to their offspring. Despite its unique appearance, pili annulati usually does not cause any significant health concerns or impact hair functionality.

Pili annulati, also known as “ringed hair” or “beaded hair,” is a rare hair disorder characterized by the presence of alternating light and dark bands along the hair shaft. These bands are typically visible under natural or ultraviolet light. The condition is benign

Causes

I. Genetic Causes

Pili annulati is primarily a genetic disorder, with mutations in specific genes causing the hair shaft’s abnormal structure. Although the exact genetic basis for pili annulati is not yet fully understood, research has identified two primary genes associated with the disorder:

  1. KRT74 (Keratin 74) gene mutation: Keratin is a structural protein that makes up hair, nails, and the outer layer of the skin. Mutations in the KRT74 gene, which encodes for keratin 74, have been linked to pili annulati. This gene mutation results in the production of an abnormal keratin 74 protein, which then disrupts the formation of the hair shaft and leads to the characteristic alternating light and dark bands.
  2. KRT86 (Keratin 86) gene mutation: In some cases, pili annulati has been associated with mutations in the KRT86 gene, which encodes for keratin 86. Similar to the KRT74 gene mutation, the KRT86 gene mutation causes the production of an abnormal keratin 86 protein, leading to the disorder’s distinctive features.

II. Inheritance Pattern

Pili annulati typically follows an autosomal dominant inheritance pattern, meaning that an individual only needs to inherit one copy of the mutated gene from either parent to develop the disorder. However, there have been cases where the disorder appears sporadically, without a clear family history. This suggests that pili annulati may also result from de novo mutations or genetic changes that occur spontaneously during conception or fetal development.

III. Hair Shaft Structure and Melanin Distribution

The hair shaft consists of three main layers: the cuticle, cortex, and medulla. In pili annulati, the hair shaft’s structure is altered, leading to the formation of the characteristic light and dark bands. The light bands are the result of the presence of air-filled cavities within the cortex layer, while the dark bands are due to the normal distribution of melanin (pigment) granules.

The exact mechanism behind the formation of these air-filled cavities is not fully understood. However, it is thought that the abnormal keratin proteins resulting from the KRT74 and KRT86 gene mutations interfere with the normal structure of the cortex layer. This disruption may lead to the development of these cavities, causing the hair shaft to exhibit the characteristic light and dark bands.

Symptoms

This detailed explanation will cover the main symptoms of Pili annulati, its underlying causes, diagnosis, and potential treatment options.

  1. Visible Bands on Hair Shaft: The most characteristic symptom of Pili annulati is the appearance of alternating light and dark bands on the hair shaft. These bands are typically more visible in natural sunlight or under ultraviolet light. The light bands are caused by air-filled cavities within the hair shaft, which reflect light differently than the surrounding, normally pigmented areas.
  2. Hair Texture: Individuals with Pili annulati may notice a change in their hair’s texture. The affected hair may become more brittle, coarse, or dry compared to healthy hair. This change in texture is a result of the structural abnormalities within the hair shaft, which can weaken the hair and make it more prone to breakage.
  3. Scalp Visibility: In some cases, the hair may appear thinner or more sparse, leading to increased visibility of the scalp. This is not due to hair loss, but rather a consequence of the hair’s altered structure and texture. The hair may appear less dense and less capable of providing adequate coverage of the scalp.
  4. Unpredictable Hair Growth: Pili annulati can affect hair growth in unpredictable ways. Some individuals may experience periods of normal hair growth followed by periods where the ringed pattern re-emerges. This unpredictable nature can make it challenging to manage the condition and maintain a consistent appearance.
  5. Distribution: Pili annulati can affect hair on any part of the body, but it is most commonly observed on the scalp. The condition can be localized, affecting only a small area, or it can be more widespread, impacting a larger portion of the hair.
  6. Age of Onset: The condition can appear at any age, but it is most commonly noticed during childhood or adolescence. In some cases, the symptoms may become less noticeable or disappear entirely as an individual ages.

Diagnosis

The diagnosis of pili annulati is made through a combination of clinical examination, microscopic examination of the hair shaft, and genetic testing. In this article, we will discuss the main diagnostic features of pili annulati and the tests used to confirm the diagnosis.

Clinical Features:

The clinical features of pili annulati include the following:

  1. Alternating bands of light and dark hair when viewed under polarized light.
  2. The hair is typically lustrous, silky, and smooth.
  3. The hair is fragile and easily breaks or falls out.
  4. The hair may have a tendency to curl.
  5. The scalp may be slightly erythematous (reddened) or scaly.

Microscopic Examination:

Microscopic examination of the hair shaft is an important diagnostic tool for pili annulati. The hair shaft is examined under polarized light, which reveals the characteristic alternating light and dark bands. The bands are caused by air spaces within the hair shaft, which create a pattern of light reflection.

In addition to the alternating bands, other features that may be seen on microscopic examination include:

  1. A “moth-eaten” appearance of the hair shaft, characterized by irregularly spaced areas of thinning or absence of pigment.
  2. A beaded appearance of the hair shaft, caused by irregularly spaced nodes along the length of the hair.
  3. The presence of trichorrhexis nodosa, which is a condition characterized by the formation of nodules or knots along the hair shaft.

Genetic Testing:

Pili annulati is a genetic disorder caused by mutations in the keratin 3 or keratin 12 genes. Genetic testing can be used to confirm the diagnosis of pili annulati by identifying the specific gene mutation responsible for the disorder.

Genetic testing is typically performed using a blood sample or a sample of cells from the inside of the cheek (buccal cells). The DNA is extracted from the sample and sequenced to identify any mutations in the keratin 3 or keratin 12 genes.

In addition to confirming the diagnosis of pili annulati, genetic testing can also be used for prenatal diagnosis in families with a history of the disorder. Prenatal diagnosis involves testing the DNA of a developing fetus to determine if they have inherited the genetic mutation responsible for pili annulati.

In summary, the diagnosis of pili annulati is made through a combination of clinical examination, microscopic examination of the hair shaft, and genetic testing. The characteristic alternating bands of light and dark hair when viewed under polarized light are the main clinical feature of the disorder. Microscopic examination of the hair shaft can reveal additional features such as a “moth-eaten” appearance or trichorrhexis nodosa. Genetic testing can confirm the diagnosis and identify the specific gene mutation responsible for the disorder.

Treatment

The main treatment for Pili annulati is to manage the appearance of the hair.

There are several different drug treatments that have been used to manage the symptoms of Pili annulati. The most common treatments include:

  1. Minoxidil

Minoxidil is a vasodilator drug that is commonly used to treat hair loss. It works by widening blood vessels in the scalp, which increases blood flow to the hair follicles and promotes hair growth. While there is limited research on the effectiveness of minoxidil for Pili annulati specifically, it has been shown to be effective for other types of hair loss, and may be worth trying for those with Pili annulati.

  1. Topical steroids

Topical steroids are a type of medication that is applied directly to the skin. They work by reducing inflammation and suppressing the immune system. In the case of Pili annulati, topical steroids can help reduce the inflammation in the hair follicles and slow the progression of the disease. Some commonly used topical steroids for Pili annulati include clobetasol propionate, betamethasone valerate, and fluocinolone acetonide.

  1. Systemic steroids

Systemic steroids are a more potent form of steroid medication that is taken orally or through injection. They work in a similar way to topical steroids, but are more effective at suppressing the immune system and reducing inflammation. Systemic steroids are generally only used in severe cases of Pili annulati, as they can have significant side effects if used long-term. Some commonly used systemic steroids for Pili annulati include prednisone and triamcinolone.

  1. Retinoids

Retinoids are a type of medication that is derived from vitamin A. They work by promoting cell turnover and reducing inflammation. In the case of Pili annulati, retinoids can help promote the growth of healthy hair and reduce the severity of the alternating light and dark bands. Some commonly used retinoids for Pili annulati include isotretinoin and acitretin.

  1. Immunomodulators

Immunomodulators are a type of medication that work by modulating the immune system. They can be used to treat a wide range of autoimmune and inflammatory conditions, including Pili annulati. Some commonly used immunomodulators for Pili annulati include cyclosporine, tacrolimus, and mycophenolate mofetil.

Alternative Treatment

There is currently no cure for this condition, but several treatment options can help to improve the appearance of the hair and reduce the visibility of the bands.

  1. Camouflaging Techniques: Camouflaging techniques are used to reduce the visibility of the light and dark bands on the hair. This can be done by using hair dyes or hair pigments that blend in with the hair color. It is important to use hair products that are safe for use on hair affected by Pili annulati.
  2. Haircuts: Regular haircuts can help to remove the damaged portions of the hair and promote healthy hair growth. It is recommended to avoid using sharp objects such as scissors or razors as they can cause further damage to the hair.
  3. Hair Oils and Conditioners: Regular use of hair oils and conditioners can help to keep the hair healthy and nourished. This can help to reduce the appearance of the light and dark bands on the hair.
  4. Wig or Hairpiece: Wearing a wig or hairpiece can be an effective way to conceal the bands and improve the appearance of the hair. This option is particularly useful for individuals who are self-conscious about their hair or have difficulty managing their hair due to the bands.
  5. Laser Treatment: Laser treatment can be used to reduce the visibility of the light and dark bands on the hair. This treatment involves the use of a laser to break down the pigment in the hair shaft. It is important to consult with a dermatologist or hair specialist before undergoing laser treatment.
  6. Hair Transplant: Hair transplant can be an effective treatment option for individuals with severe Pili annulati. This involves transplanting healthy hair follicles to the affected area of the scalp. It is important to consult with a hair specialist before undergoing hair transplant surgery.

In conclusion, while there is no cure for Pili annulati, several treatment options can help to improve the appearance of the hair and reduce the visibility of the light and dark bands. It is important to consult with a dermatologist or hair specialist before undergoing any treatment for this condition. Regular hair care and maintenance can also help to keep the hair healthy and reduce the impact of Pili annulati.

References