|SYMPOSIUM ON ANDROGENIC ALOPECIA - REVIEW ARTICLE
|Year : 2022 | Volume
| Issue : 2 | Page : 63-68
Androgenetic alopecia: Clinical features and trichoscopy
Shashank Bansod1, Aseem Sharma2, Madhulika Mhatre3
1 Hi-Tech Skin Clinic and Hair Transplant Centre, Nagpur, Maharashtra, India
2 Skin Saga Centre for Dermatology, Mumbai, Maharashtra, India
3 Department of Dermatology, Wockhardt Hospitals, Mumbai, Maharashtra, India
|Date of Submission||03-Jan-2022|
|Date of Decision||02-Jun-2022|
|Date of Acceptance||04-Jun-2022|
|Date of Web Publication||26-Aug-2022|
Skin Saga Centre for Dermatology, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
Androgenetic alopecia, known alternatively as male pattern baldness when men are affected, and female pattern hair loss, when it affects women, is a form of alopecia characterized by miniaturization – a process wherein thick, long terminal hair are converted to short, thin, miniaturized hair due to the effect of dihydrotestosterone. Various pathogenetic mechanisms exist that support the process. Due to the unusually high disease burden and the psychosocial affliction, a lot of research in underway in the field. Clinically, this subtype of patterned hair loss presents with typical and atypical patterns presenting with thinning of hair and / or balding, or both. It is of paramount importance to recognize and grade the disease early to administer appropriate therapy. Trichoscopy also plays a major role in diagnosing, prognosticating and even monitoring patient response to therapy.
Keywords: Androgenetic alopecia, clinical grading, male pattern baldness, trichoscopy
|How to cite this article:|
Bansod S, Sharma A, Mhatre M. Androgenetic alopecia: Clinical features and trichoscopy. Clin Dermatol Rev 2022;6:63-8
| Introduction|| |
Androgenetic alopecia (AGA) is a genetic disorder characterized by gradual and progressive thinning of scalp hair occurring in both males and females. The large, thick, pigmented anagen hair is commonly targeted by dihydrotestosterone as a natural progression of the disease, and the hair gets thinned out leading to a visibly balding scalp. The grade of severity is more in males.
AGA has become more of a social disorder where most of the affected individuals suffer from loss of self-confidence which, may even progress to frank depression in a few.
| Epidemiology|| |
AGA is the most common form of patterned baldness across all races and sexes. It has been seen that the incidence and severity of AGA are more common in Caucasians than in other races, while the lowest global prevalence is found among oriental races.
The exact prevalence of AGA is difficult to establish due to different figures stated in multiple studies in pooled data. However, it can be concluded beyond doubt that prevalence increases with age in all ethnicities. Hamilton quoted that the presence of AGA in males is 30% by the age of 30 years, which progresses to 50% by the age of 50 years. Although hair thinning may begin in puberty itself, males are affected earlier in their life as compared to females. In a South African study, it was quoted that the prevalence of AGA in males was around 14% and that in females was around 3%. In studies of the Asian population, it was observed that the prevalence of AGA across all ages was about 20% in males and 5%–6% in females, which was lower than that in the Caucasian population. From an Indian perspective, studies with large sample sizes have shown a prevalence of 58% in males aged between 30 and 50 years. Among women with female pattern hair loss (FPHL), a temporal relationship between excess androgens and alopecia has not been established. Hence, the term FPHL is preferred over female AGA, as previously used.
Epidemiological studies of AGA in women are fewer in number. A study by Norwood, showed a total prevalence of around 19% in a population of 1006 Caucasian patients. In a Chinese population study, the prevalence was only 6.0% and a Korean study had a relatively similar lower prevalence of 5.6%, suggesting that like in men, the prevalence is considered to be lower in oriental races compared to Caucasians., The incidence of AGA in women also tends to increase with age.,
In a statistical analysis on AGA by Kubra et al., it was concluded that in men across all ages, the most common grade of the presentation was grade 3 while in women it was grade 1. It was also concluded that the frequency of AGA was not statistically different in females with or without a family history, while in men frequency was more with positive family history.
It should be noted that experts have suggested that female AGA is not exactly the female counterpart of male AGA. A better term for female AGA would be “female pattern alopecia” or “FPHL.” The clear difference in the clinical pattern of male and FPHL suggest that these are two separate entities. This is also based on studies which have shown no clear relation between excess testosterone levels and FPHL.
| Clinical Features|| |
AGA is the most common cause of baldness in both males and females. The symptoms start to develop in the teenage after which the hair loss progresses gradually into different patterns.
In males, AGA is genetically determined and presents as a reduction in hair density due to hair miniaturization, in a characteristic pattern.
Initially, the frontotemporal area and vertex are two areas preferentially affected. As the hair loss progresses further, terminal hair is continuously replaced by vellus hair in an orderly manner without any skip areas, leading to hair loss in the mid frontal, temple, and vertex areas.
The hair loss is not equal in all three mentioned areas; some men undergo hair loss in the frontal area while some are bald over the vertex. This gives rise to various hair patterns, which are defined further in the classification of AGA in males.
In females, hair loss is said to be multifactorial and the role of androgens is not well defined, so it is considered a different condition named FPHL. Just as in males, hair miniaturization in females begins in teenage, which progresses further with increasing age. There is diffuse hair loss, especially involving frontal, central, and parietal areas of the scalp in females too.
Patterns of hair loss in females
In the first pattern diffuse thinning of upper biparietal and vertex areas of the scalp happens, while the frontal hairline is preserved. This pattern is included in different hair loss scales, Ludwig's scale being the most commonly used among those.
In the second pattern, described by Olsen has the involvement of frontal, bitemporal, and vertex areas of the scalp in a Christmas tree distribution.
Finally, a third pattern presents with involvement of frontotemporal areas of the scalp as seen in males, but this is quite uncommon.
| Scales and Classification|| |
Classification of AGA is required for accurate grading of baldness to prognosticate and standardize the treatment. The patterns and progression of alopecia differ in males and females; hence the scaling systems are different too.
In male AGA, numerous classification systems have been described, each one having its own advantages and pitfalls. Over the years, many workers came up with their classification systems. Few important classifications in male and female patterned baldness developed over the years have been mentioned in [Table 1].
As of now, the most widely used classification is Hamilton-Norwood classification, which was described by Norwood which is essentially an update to Hamilton's original classification. It has seven types, instead of eight as in the original Hamilton classification, with five subdivisions [Table 2].
These stages of receding hairline are common and more or less similar to that described by Hamilton in his classification. However, Norwood recognized common progression pattern of hair loss, from type two to type five which he defined as Type A and added it to the above classification.
Type A Classification
- Anterior hairline border progresses to the rear without having an island of hair in the mid frontal area
- The absence of simultaneous development of the bald area over the crown. Instead, there is a progression of frontal recession toward the rear end of the scalp.
- Scattered sparse hair in the area of hair loss
- The fringe area of hair over back and sides of the scalp are wider and reach higher overhead as compared to the standard Norwood classification.
The Type A variants in the Hamilton-Norwood classification are described in [Table 3].
The addition of Type A and modifying the original Hamilton's classification by Norwood is called Hamilton-Norwood classification and this included almost every clinical presentation of male AGA [Figure 1] and [Figure 2] as live examples of grading].
|Figure 1: Anterior variant of Hamilton-Norwood Scale for AGA. AGA: Androgenetic alopecia|
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|Figure 2: Vertical variant of Hamilton-Norwood Scale for AGA. AGA: Androgenetic alopecia|
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Just like others, this classification also has some drawbacks.
Drawbacks of the Hamilton-Norwood classification are:
- Too intricate to remember
- Its reproducibility has been proven unsatisfactory.
The most commonly used classification of female pattern baldness also is proposed by Ludwig.
It consists of three grades as described in [Table 4].
In all these grades of Ludwig's classification, preservation of frontal fringe is emphasized [[Figure 3] example of Ludwig grade 3]
|Figure 3: Grade III of Ludwig scale for FPHL. FPHL: Female pattern hair loss|
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Its major disadvantages are that:
- It did not incorporate front vertical accentuation
- Females with balding in male pattern baldness could not be classified by this classification.
Ebling and Rook (1975) modified Ludwig's classification to five grades and included the male pattern of baldness occurring in females.
In this grading grade 3 was modified as continued diffuse hair loss instead of denudation, as mentioned in Ludwig's classification, and grade 4, frontotemporal recession in continuation with grade 3 in grade 5, there will be complete hair loss over the scalp resembling male pattern baldness.
This was a required update after Ludwig's scale covering a wider spectrum of female alopecia.
Olsen (1994) in his classification incorporated frontal vertical alopecia which he described as Christmas tree patterns. This pattern can be seen in all stages of alopecia [[Figure 4] as an example of Olsen's frontal accentuation].
|Figure 4: Grade II of Olsen scale for FPHL. FPHL: Female pattern hair loss|
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Savin (1992) proposed a 9-point scale to clinically quantify hair loss in women.
The latest classification is by Sinclair (2004 is used for the self-reported perception of hair loss severity in females by comparing with five-colored photographs of women's scalp with centrally parted hair.
The Sinclair Scale was documented in 2005 to fill the lacuna of the low sensitivity of the existing scales for FPHL, especially since all the preceding scales can miss subtle, early changes of the disease. This is a photographic scale, using visual analogs of the 5 stages of patterned hair loss in women – normal (I), central partition widening (II), lateral volume loss to the mid partition (III), anterior recession (IV), and advanced alopecia (V). This has also been upgraded to include trichoscopic derivation in 2019.
Sex-neutral classification of alopecia
The sex-neutral classification was proposed by Bouhanna (2000) and Lee (2007).
A polyfactorial classification, proposed by Bohannan can be used for both males and females. This scale is found to be useful to address hair changes during treatment and also to decide the indication of hair transplant.
Lee et al. in 2007 proposed a unique classification by the name “Basic and Specific classification.” This classification is considered more comprehensive, systematic, and not limited to either sex.
BA (basic) type represents the shape of the anterior hairline based on 4 English alphabets; L, M, C, and U.
SP (specific) types are F and V and represent the density of hair in the frontal area and vertex.
The final type is determined by combining basic and specific types [[Figure 5] – pictorial representation].
|Figure 5: Basic and Specific Assessment (BASP). BASP: Basic and specific classification|
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| Trichoscopic Features of Androgenetic Alopecia|| |
AGA is a clinical diagnosis but trichoscopy helps immensely in confirming the diagnosis and prognosticating it, especially in the early stages.
In females, it helps to differentiate between the other close differentials of female patterned alopecia which include diffuse alopecia areata and telogen effluvium.
The trichoscopic findings in AGA, which are similar in both males and females have been elaborated in [Table 5],, and enumerated in [[Figure 6], courtesy – Dr. Madhulika Mhatre, Wockhardt Hospitals].
| Conclusion|| |
AGA is a progressive hair disorder in which hair miniaturization occurs. It starts in adolescence in all ethnicities but Caucasians are more severely affected than other races.
AGA and female patterned baldness are clinical diagnoses but trichoscopy helps in assessing the severity of baldness and in ruling out other differentials, especially in FPHL.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]