Alopecia - an overview

Alopecia

Introduction

This chapter provides an overview of alopecia (excluding the genetic hair shaft defects). Differentiating between scarring and non-scarring alopecia is particularly important because scarring alopecia is irreversible and so early intervention is required in order to try and minimise hair loss.

This chapter is set out as follows:

Aetiology

The hair cycle

Hair follicles undergo a repetitive sequence of growth and rest known as the hair cycle. To understand the different causes of hair loss it is important to have a comprehension of the hair cycle:

Anagen - is the period of active growth and may last for several years. Under normal circumstances 80-90% of hair follicles on the human scalp are in anagen at any one time
Catagen - at the end of anagen, epithelial cell division declines and ceases, the hair follicle enters an involutionary phase known as catagen
Telogen - the period between the completion of follicular regression and the onset of the next anagen phase is known as telogen, during which time the hair is shed
Kenogen - in the human scalp, hair follicles may remain in a state of latency, also known as kenogen, for a prolonged period after the hair is shed

The term telogen effluvium is broadly used to describe any cause of diffuse hair shedding in the telogen phase, and results from the premature termination of anagen with a subsequent reduction in the length of the hair cycle

Clinical findings

Understanding the normal scalp

Dermoscopy is being increasingly used to help diagnose the type of alopecia, and consequently reduce the need for scalp biopsies, which in themselves may not be diagnostic
In the normal scalp several hairs can be seen in each follicular unit, all with a similar width. There is often mild loose and non-perifollicular scale

A logical approach to alopecia

1. Is it non-scarring or scarring?

2. If non-scarring is it male or female pattern alopecia?

3. If non-scarring is the hair loss diffuse?

4. If non-scarring is it more patchy?

5. Scarring alopecia - is it one of the cicatricial (circular / oval shaped patches of alopecia) causes or is it something else?

1. Non-scarring or scarring alopecia?

The first step to making a diagnosis is to differentiate whether the alopecia is non-scarring or scarring:

Non-scarring alopecia

No clinically visible inflammation is noted in most cases
Atrophy absent
Tufting absent
Tends to have preserved follicular openings

Scarring alopecia (figure 19)

Clinical inflammation is frequently, but not always, present
Loss of follicular openings
Atrophic, often with a shiny appearance
Variable dermoscopic features, which may include follicular heads having a black 'clubbed' appearance
'Dolls hair' tufting - mainly seen in folliculitis decalvans, and occasionally in other causes of long-term severe scarring

2. Non-scarring alopecia - male and female pattern

Male pattern alopecia (figures 1-2)

Recession of the frontal hair line, mainly in a triangular pattern is the characteristic finding, later followed by thinning of the vertex
Dermoscopic features - in affected areas there will be fewer hairs in each follicular unit and more than 20% of the hairs will be small and fine ie miniaturised
Refer to the related chapter Alopecia - male and female pattern alopecia for more information

Female pattern alopecia (figure 3)

The Ludwig pattern - is characterised by a diffuse thinning of the centroparietal region with maintaining of the frontal hair line. It is the most common type in women, occasionally also observed in men
The Christmas tree pattern - this is similar to the Ludwig pattern in that the Christmas tree pattern shows diffuse centro-parietal thinning, but additionally, the frontal hair line is breached
Dermoscopic features - as above
Refer to the related chapter Alopecia - male and female pattern alopecia for more information
If associated with hirsutism or other signs of virilisation also refer to the related chapter Hyperandrogenism

3. Non-scarring alopecia - diffuse

Acute:

Drugs (acute and/or chronic)

In particular chemotherapy agents, which cause hairs to fall out in their anagen growth phase, referred to as anagen effluvium (figure 4)

Acute telogen effluvium

Normally occurs two to three months after a triggering event such as pyrexia (in particular a body temperature of 102.5 degrees Fahrenheit and above), child-bearing, major surgery, weight loss and certain medications
In one-third of cases no trigger is identified
Unless the trigger is repeated, spontaneous complete regrowth occurs within three to six months

More gradual:

Other causes of telogen effluvium

Thyroid disorders (figures 5-6)
Profound iron deficiency anaemia (figure 7) can cause a diffuse hair loss. The association between iron deficiency and no or mild anaemia and chronic diffuse hair loss is controversial, however, a trial of iron supplements is worthwhile for ferritin levels < 40
Increasing age
Many drugs have been implicated with hair loss in the telogen phase although good evidence for a link is not often evident. A dose-related diffuse alopecia is commonly seen with acitretin
Crash dieting
Various - disorders causing malabsorption, hepatic and renal disorders, malignancy, SLE and dermatomyositis can all cause telogen hair loss
Zinc deficiency, both acquired (from long-standing parenteral nutrition) and inherited, can be associated with a severe telogen effluvium. Acrodermatitis enteropathica is a rare genetic disorder associated with the malabsorption of zinc and characterised by diarrhoea, an inflammatory rash around the mouth and / or anus, and alopecia
Alopecia areata: occasionally the initial hair loss may be diffuse
Secondary syphilis (figure 8): is non-inflammatory and can present with a diffuse pattern of alopecia, a moth-eaten pattern or a combination of both. The scalp is the most commonly affected area. However, the eyebrows, eyelashes, axilla, pubis, chest, and legs can also be affected. Alopecia syphilitica often accompanies other mucocutaneous symptoms of secondary syphilis, but it can be the only presenting symptom
Investigations - all patients with diffuse alopecia require a FBC, ferritin and TFT. The need for any additional tests depends on the history / examination as above

Chronic telogen effluvium (CTE)

CTE is a primary idiopathic and often self-limiting condition affecting middle-aged women
Patients, often with longer and thick hair, describe large amounts (often 50%) of hair loss and the patient may bring the hair to the consultation
On examination the patient has a good head of hair appropriate to their age with no widening of the central parting line
Despite of the shortened hair cycle, which may go on for several years, women with CTE should be reassured that the natural history is NOT that of a progressive alopecia (unless the patient also has female pattern alopecia, the two conditions can co-exist)
There is no treatment other than reassurance
Occasionally such patients may have a dysmorphophobia, a psychiatric condition, the hallmark of which is a fixation on an imaginary flaw in the patient's physical appearance, or in cases in which a minor defect truly exists the patient exhibits an inordinate amount of anguish
Provide a patient information leaflet

4. Non-scarring alopecia - more patchy

Alopecia areata (figure 9)

The characteristic initial lesion is a circumscribed, totally bald, smooth patch. The skin within the bald patch is normal or slightly reddened. Short broken hairs (exclamation mark hairs) are often seen around the margins of active expanding patches of alopecia
Dermoscopic features - yellow dots and also black dots if a hair is broken off at the root, coiled ‘pig tail’ hairs (not specific but most commonly seen in alopecia areata), exclamation mark hairs
Refer to the related chapter Alopecia areata for more information

Tinea capitis (figure 10)

Can cause non-scarring or scarring alopecia
Hair loss tends to be patchy, but is often associated with subtle inflammation / scale
Dermoscopic features - scale, broken hairs with black dots, comma-shaped hairs
Refer to the related chapter Tinea capitis for more information

Trichotillosis (formerly called trichotillomania) - hair pulling (figures 11-15)

Trichotillosis is a behavioural disorder characterised by compulsive hair pulling associated with an increase in tension prior to the pulling and a sense of relief when the hair is pulled out
It is more common in women and can occur in people from all walks of life
The hair manipulations frequently occur in patients engaged in sedentary activities
Distribution

The patches may be single or multiple
The frontal and temporal scalp are most commonly affected, but any site can be involved
The degree of involvement may vary from only a few square centimeters to large areas of scalp

Unlike in alopecia areata

The patches of alopecia may take on unusual shapes
It is uncommon for the hair to be completely lost within a patch of alopecia, and the remaining hair is firmly anchored in the scalp
Dermoscopic featues - hair length is not uniform. Other features can include newly growing short hairs with tapered ends, broken short terminal hairs, vellus or indeterminate hairs, black dots, empty follicular orifices

The establishment of a good relationship between the physician and patient or parents of the affected child is important, as is the making of a confident diagnosis
Management is mainly psychological support. Attempts should also be made to try and identify triggers for the patient's behaviour

Traction alopecia (figures 16-17)

Is due to certain hair styles which cause a sustained pull on the hair
The pattern of hair loss is often distinctive and reflects the direction of traction
Traction alopecia is most commonly seen in Afro-Caribbean hair styles when the hair is tightly braided. The hair loss commonly begins in the temporal regions and in front of / above the ears
The presence of retained hairs along the frontal and / or temporal rim, termed the “fringe sign,” is a common finding in both early and late traction alopecia, and is a useful clinical marker of the condition
Can be associated with headaches
Changes are reversible if the style is changed early - if braids continue to be used their directions should be alternated, and must be loose
If there is no history of significant traction the term primary marginal alopecia is sometimes used

5. Scarring alopecia

Infection

Bacterial infection eg a severe staphylococcal infection
Tinea - refer to the related chapter Tinea capitis for more information (figures 19-20)

Cicatricial alopecia - circular-oval shaped patches of scarring

Lichen planopilaris (figure 21)

Follicular erythema and keratotic plugs, which are commonly located at the periphery of expanding areas of alopecia
Dermoscopic features - perifollicular scale and inflammation
Refer to the related chapter Lichen planus - follicular lichen planus for more information

Discoid lupus erythematosus - DLE (figure 22)

Much more common in women
Scarring alopecia occurs in 20% of men and 50% of women with DLE
Although DLE often presents on the face, the scalp can be the only affected site
The scalp is often itchy
Affected patches are erythematous and scaly with follicular plugging
Dermoscopic features - often chaotic with yellow rough looking follicular plugs, telangiectasia and white or dark areas. Erythema and scale may be more pronounced around the periphery of areas of alopecia
Patients are treated along the lines of cutaneous lupus with UV-protection, super-potent topical steroids, intralesional steroids and antimalarial therapy (hydroxychloroquine +/- mepacrine). Other treatments sometimes used include retinoids (studies undertaken used acitretin), dapsone, thalidomide and occasionally immunosuppressive therapies (refer to the related chapter on Lupus erythematosus for more information)

Folliculitis decalvans (figure 23)

Patients usually present with one or more round patches of scarring alopecia usually surrounded by pustules, crusting and sometimes erosions
Nearly always starts on the crown and expands outwards
Dermoscopic features - marked 'dolls hair' tufting, scale, perifollicular and interfollicular erythema, pustules. Crusting will be present if the inflammation is very active
Refer to the related chapter Folliculitis decalvans for more information

Central centrifugal cicatricial alopecia CCCA (figure 24)

Is a condition that predominantly affects women of African ethnicity
It usually presents in the fourth decade with a female to male ratio of approximately 3:1
The aetiology is unknown although it is probably genetic in some
Traction (from heated styling instruments or chemical straighteners), pattern hair loss and iron-deficiency may co-exist. CCCA is also associated with hirsutism
Clinically there is a diffuse scarring alopecia that begins at the crown and spreads forwards. The alopecia is incomplete with a number of hairs remaining within the area of scarring. There tends to be little or no erythema
Dermoscopic features - in dark skin the normal scalp appearance is a pigment network with regular white dots. In CCCA there are white-grey halos around follicles and subtle irregular white dots
Mycology to rule out tinea capitis is recommended
No ideal treatment currently exists. Minimal hair grooming is recommended, but many patients find this difficult. If there are signs of inflammation (clinically or histologically) the use of a potent topical or intralesional corticosteroid may arrest/slow progression. Occasionally pustules are seen in which case a systemic tetracycline such as doxycycline or lymecycline may be of value. Other treatments occasionally used in the presence of inflammation include those used for lichen planopilaris

Pseudopelade of Brocq (figure 25)

Asymptomatic, slowly progressive, patchy cicatricial alopecia with no evidence of inflammation
Two aetiological theories exist

It is primarily an atrophic condition
It is the end point of inflammatory conditions such as follicular lichen planus

There is no known effective treatment

Other causes of scarring alopecia

Frontal fibrosing alopecia (figure 26)

A type of lichen planus
Most common in post-menopausal women but can affect other age groups and rarely men
Hair loss first affects the arms and legs, sometimes years before the eyebrows and then the scalp
In the scalp it presents as a progressive symmetric band-like alopecia, affecting the frontal hair line, the pre-auricular scalp, and less commonly all the way around the hairline
Dermoscopic features - follicular prominence with hyperkeratosis (excess scaling) around hair follicles, inflammation can be subtle or absent
Refer to the related chapter Lichen planus - follicular lichen planus for more information

Acne keloidalis nuchae

Acne keloidalis nuchae (AKN) is a condition characterised by follicular-based papules and pustules that form hypertrophic or keloid-like scars. AKN typically occurs on the occipital scalp and posterior neck and develops almost exclusively in young, African-American men. Refer to the related chapter Acne Keloidalis Nuchae for more information

Dissecting cellulitis (figure 27)

More common in black patients and between the ages of 18-40
A variant of acne conglobata
Presents with painful nodules and abscesses that taken on a cerebriform appearance. Can become extensive across the scalp
Early intervention can prevent scarring
Treatment - patients should be referred urgently, refer to the chapter Dissecting cellulitis

Pemphigus (figure 28)

Pemphigus vulgaris affects middle-aged patients causing mucosal lesions, flaccid blisters on the skin and erosive scalp changes
Pemphigus foliaceus is less severe than pemphigus vulgaris and mucosal lesions are uncommon

Cicatricial pemphigoid

Mainly affects elderly patients. This bullous disorder involves the eyes and / or other mucosal surfaces causing painful erosions and scarring. Patients with cutaneous involvement present with tense blisters and erosions, often on the head and the neck, with scalp involvement in 10% of cases

Erosive pustular dermatosis of the scalp (figures 29-31)

Affects the elderly with varying degrees of scarring associated with yellow-brown crusts, pustules, lakes of pus, erosions and ulceration. Previous UV damage, cryotherapy or other physical insults to the skin appear to play a role. Treatment is with super-potent topical steroids and UV protection

Linear morphoea 'en coup de sabre' (figure 32)

An atrophic band-like area of alopecia on the frontoparietal scalp and forehead

Follicular mucinosis (figures 33-34)

Benign follicular mucinosis: sometimes referred to as alopecia mucinosa - a benign condition. Early signs of the disease are the presence of grouped follicular papules arising in patches / plaques, usually 2-5 cm in diameter. Hair loss is common from the affected follicles. In some patients the condition resolves spontaneously and the hair regrows. In more severe disease complete follicular destruction prevents normal hair growth. Other features can include acneiform lesions
Folliculotropic mycosis fungoides: this is due to a cutaneous t-cell lymphoma, and is characterised by a more generalised chronic form in a slightly older age group, with larger and more numerous plaques on the scalp, face and also the extremities

Images

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Investigations

Investigations depend on the clinical context but can include:

Swabs of pustules for C & S - the contents of the pustule should be expressed
If tinea is suspected, scrapings of scale and plucked hairs should be sent for mycology
Non-scarring alopecia can be multifactorial so consider the following blood tests:

Diffuse alopecia / female-pattern alopecia / undetermined alopecia - FBC, ferritin, U&E, LFT, TFT, zinc levels, and vitamin D. The need for any additional tests depends on the history / examination eg ANA / ENA for suspected lupus, VDRL for suspected syphilis
Female patients presenting with alopecia and hirsutism / irregular periods or other signs of virilisation need further investigations - refer to the related chapter Hyperandrogenism

Biopsies

Scalp biopsies are not always needed and in some case do not provide a definitive diagnosis. The main reason to biopsy is for cases of diagnostic uncertainty, especially if the outcome may affect management
If a scalp biopsy is to be performed it is worth checking with a local pathologist as to what is required - some departments prefer two 4 mm punch biopsies, one each for horizontal and vertical sectioning. Biopsies should be taken from active sites (as opposed to scarred sites) and angled at the same direction as the hair to try and get the whole hair follicle. If considering lupus erythematosus a sample should also be sent for direct immunofluorescence
In general the decision as to whether or not a biopsy is needed is best left to a specialist, who will also be in a better place to correlate the histology result and clinical findings should a biopsy be performed

Management

Management depends on the clinical context - refer to the clinical findings and investigations above, and related chapters (top right)

Who to refer

Patients with scarring alopeica require an urgent referral - once scarred the alopecia is irreversible
Patients with non-scarring alopecia may also need referring as follows:

Diagnostic uncertainty
Some cases of alopecia areata
Management issues eg trichotillomania
If associated with moderate-severe emotional distress
If a wig is required - wigs can be used as effective ways to cope with alopecia. Local dermatology departments may be the best contact in terms of obtaining / finding out where to obtain wigs on the NHS. Patients are given a choice of monofilament acrylic wigs or synthetic acrylic wigs. Human hair wigs are normally reserved for patients found on patch tests to be allergic to acrylic wigs

Other resources

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Alopecia - an overview

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Dr.Milan Dayani

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