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June 2007: Acne

What are the various types of acne?

Which conditions present in an acneiform way?

How can treatment be tailored to presentation?

What are the various types of acne?

Which conditions present in an acneiform way?

How can treatment be tailored to presentation?

Acne is a term that covers a spectrum of different conditions. the most common of these is acne vulgaris, which is reported to affect up to 80% of people at some time between the ages of three and 18 years.1 Up to 30% of those affected have acne severe enough to warrant treatment.2

In one study it was reported that 3.1% of all patients aged 13 to 25 who attended in primary care had a primary diagnosis of acne vulgaris.3 Overall incidence is the same in men and women, with a peak incidence at 17 years of age.2

The number of adults affected by acne has increased over the past few years, although the reason for this remains unclear.4 The right approach to treatment can greatly improve the lives of those affected.

1 Closed Comedones

The pilosebaceous unit forms the heart of the acne lesion. During puberty the pilosebaceous units enlarge under the influence of testosterone and fill with sebum, which becomes visible macroscopically. Excess keratin, produced by abnormal follicular hyperkeratinisation, mixes with the sebum and produces the typical dark ‘blackhead' or open comedone. If the unit is closed the sebum remains lighter, producing a white, closed comedone.

If a patient presents with acne that mainly consists of comedones and mildly inflamed pilosebaceous units the treatment of choice is with a topical retinoid, such as adapalene, and benzoyl peroxide. This combination reduces inflammation and comedones.

Where there are many large closed comedones topical treatment may not be as successful. In these cases hyfrecation can be used, following the application of anaesthetic cream, by gently applying the hyfrecator tip, on a low setting, to the epidermis.

This treatment has been shown to work well.5

2 Pustules

The typical pustules seen in acne vulgaris are caused when the plugs of sebum that form comedones become colonised by bacteria and an inflammatory reaction occurs.

The most common bacterium detected is Propionibacterium acnes. This is a microaerophilic bacterium that causes an inflammatory reaction via a number of different mechanisms. Initially, it stimulates the production of proinflammatory mediators that diffuse through the follicle wall. It also activates toll-like receptors6 on monocytes and neutrophils, leading to the production of cytokines and TNF.

It is thought that some patients may have a hypersensitivity reaction to P. acnes, which is why the condition affects different individuals in different ways.

3 Acne Agminata

Acne agminata, also known as lupus miliaris disseminatus faciei, is an uncommon inflammatory dermatosis characterised by yellow-red papules on the central area of the face.

Acne agminata was once considered to be a tuberculous condition. However, as cultures have never revealed the presence of mycoplasma bacteria, it is now believed that it is more likely to be an extreme variant of granulomatous rosacea.

Aetiology and pathogenesis are relatively unknown. The condition usually lasts for around one to three years, before resolving spontaneously. Scarring is common and can produce lasting disfigurement.

If the diagnosis is in doubt then biopsy may be required.

Treatment options include low-dose prednisolone, dapsone, tetracyclines, antimalarials, pyridoxine hydrochloride, riboflavin and isotretinoin.

4 Acneiform Eruptions

As with acne vulgaris, acneiform eruptions may consist of comedones, pustules, cysts and nodules, which can be misleading when it comes to making an accurate diagnosis. These eruptions can be associated with many different diseases and aetiologies. These include:

• Drugs, for example oral and topical steroids

• Tuberous sclerosis

• Secondary syphilis

• Coccidioidomycosis

• Eosinophilic pustular folliculitis.

Management initially consists of trying to establish the cause of the rash and may include biopsies, withdrawal of drugs, cultures and serological testing. Treatment can then be focused specifically on the cause. For example, with steroid-induced acne the withdrawal of the drug will generally lead to an improvement of the rash.9 Pimecrolimus may be a useful alternative treatment.10

5 Acne Rosacea

Rosacea is defined as a persistent erythema of the central portion of the face, present for at least three months. It is often associated with other features, such as flushing, telangiectasia, papules and pustules, and, to a lesser extent, stinging, burning, oedema and a dry coarseness of the surface of the skin.

In 2002 the National Rosacea Society reclassified rosacea into four subgroups:7

• Erythematotelangiectatic rosacea

• Papulopustular rosacea

• Phymatous rosacea

• Ocular rosacea.

The cause of rosacea is unknown, but various factors are known to play an important role. These include:

• Vasculature

• Climatic exposure

• Matrix degeneration

• Chemicals

• Ingested agents

• Pilosebaceous unit abnormalities

• Infection.

Spicy foods, alcohol and hot beverages may trigger a flushed face in patients with rosacea. Drugs such as amiodarone, topical steroids, nasal steroids and high doses of vitamins B6 and B12 may cause flares.

Which subtype affects which person is thought to vary depending on their sensitivity to these triggers. Differential diagnoses include sarcoidosis, lupus erythematosus, perioral dermatitis and seborrhoeic dermatitis.

6 Severe Rosacea

Rosacea is usually a chronic mild condition that responds well to topical and oral antibiotics and changes in lifestyle, such as reducing consumption of spicy foods and alcohol. However, in some cases, such as the one shown, it can be more severe.

Oral antibiotics had failed to help this patient and she was referred to secondary care, where she was treated with oral isotretinoin for four months. She responded very well and, after this course of treatment, she was maintained with a daily application of topical metronidazole.

One study compared oral and topical retinoids and found that both were beneficial, with an added benefit when both were used simultaneously.8

7 Nodulocystic Acne

Nodulocystic acne is much more common than its severe form, acne conglobata. The inflamed pilosebaceous unit becomes blocked, leading to the formation of a sebaceous cyst.

In the absence of acne these cysts tend to occur as single lesions. However, post-acne cyst formation can produce multiple cysts that vary in size, causing the patient to appear disfigured, especially when they occur on the face or neck.

Surgical treatment may be required, either by formal excision of the cysts if they are large or by hyfrecation or light cautery if they are small and multiple. Isotretinoin has proved to be an invaluable aid in the fight against the more severe form of nodulocystic acne, though caution is needed in women because of its teratogenic effects. The debate as to whether its use is related to an increased risk of suicide is still ongoing.

8 Acne Conglobata

Acne conglobata is an uncommon form of severe acne, characterised by the formation of interconnecting abscesses, cysts and severe scarring. The nodules that form are usually found on the chest, shoulders, back, buttocks, upper arms and face.

Acne conglobata may develop as a sudden deterioration of existing active acne, or may occur as a resurgence of acne that has been quiescent for a number of years. The condition affects men more than women, and usually occurs in patients aged 18 to 30 years, although rarely it can be seen in infants.

Treatment of choice is isotretinoin. Alternatives include oxytetracycline, erythromycin or dapsone. If there are systemic complications a course of oral steroids may be helpful.

This condition usually requires referral to secondary care.

9 Acne Excoriee

Acne excoriee is very similar in appearance to acne vulgaris. It is a form of dermatitis artefacta caused by persistently picking the skin, hence its alternative name of dermatillomania.

Close inspection reveals multiple areas of inflammation and crusting, but an absence of comedones and pustules usually associated with acne vulgaris. The condition is more common in women than men, and, similar to acne vulgaris, is more common in teenagers. It tends to affect the face, neck, chest and back.

Unlike acne vulgaris, persistent picking means that this condition responds poorly to traditional acne remedies and may last for many years. Treatment can be difficult, but cognitive behaviour therapy, psychotherapy and hypnosis may be useful.

10 Perioral Dermatitis

It is not uncommon for acne to affect women in their early thirties, even if the condition wasn't present during the patient's teenage years. Another condition that has a similar appearance and occurs in a similar age group is perioral dermatitis.

Affecting, as the name suggests, the perioral area and nasolabial folds, perioral dermatitis usually occurs in women aged 30 to 45 years. Although the cause is unknown, it often follows the use of topical steroids.

Typically, a topical steroid is applied to a lesion that appears to be a case of mild eczema. The steroid worsens the rash, so stronger steroids are applied, leading to pustule formation and marked erythema.

Although stopping the steroid will usually help, a gradual reduction in strength may be required if higher strength steroids have been used. In severe cases oral antibiotics, such as doxycycline, may also help.

11 Folliculitis

Folliculitis is defined histologically as the presence of inflammatory cells within the wall or lumen of a hair follicle.

Folliculitis can appear very similar to acne. However, in acne follicular inflammation is a secondary event that occurs as a result of follicular obstruction, abnormal keratinisation and secondary bacterial colonisation.

Unlike acne, folliculitis can affect patients of any age on any area of the body where hair follicles are present.

There are many causative organisms. These include Pseudomonas folliculitis, and infection can occur after the use of a hot tub or Jacuzzi.

Folliculitis usually responds well to a course of oral antibiotics, such as flucloxacillin or erythromycin. In recurrent cases antibacterial soaps and advice about good hand washing technique may be helpful.

12 Pseudofolliculitis Barbae

Pseudofolliculitis barbae is a sterile condition that affects the beard area.

It is very similar in appearance to folliculitis, and is most common in African-American men and other ethnic groups with thick, coarse, curly beard hair.

Treatment involves advising patients to:

• Let the hair grow for 30 days to eliminate ingrown hairs

• Use a cleanser twice daily and a moisturing shaving foam

• Use single-blade razors

• Shave in the direction of the follicle, not against it, and not to stretch the skin.

In severe cases an oral tetracycline or laser hair removal may help. If all else fails the patient should consider growing a beard.

In patients who use triple- and quad-bladed razors, beard hair has an increased tendency to grow beneath the surface of the skin, where it acts as a foreign body and causes inflammation. In the case shown the patient's skin improved after he changed to a single-blade razor.

One of the potential complications of this condition is scarring.


Nigel Stollery
GP, Kibworth, Leicestershire and clinical assistant in dermatology, Leicester Royal Infirmary

Further reading

Prodigy guidance is available at:

Closed comedones. In patients with

a large number of closed comedones topical treatment may not be successful and patients may require hyfrecation Figure 1: Closed comedones Pustules are caused by plugs of sebum becoming colonised with bacteria Figure 2: Pustules Acne agminata is characterised by yellow-red papules on the central area of the face. The condition usually lasts for one to three years before resolving spontaneously Figure 3: Acne agminata Figure 9: Acne excoriee Acneiform eruptions have a similar presentation to acne vulgaris. Initial management consists of establishing the cause of the rash Figure 4: Acneiform eruptions Rosacea is defined as a persistent erythema of the central portion of the face Figure 5: Acne rosacea Severe rosacea. Patients may require referral to secondary care Figure 6: Severe rosacea Nodulocystic acne may require surgical treatment, either by formal excision of the cysts, or by hyfrecation or light cautery Figure 7: Nodulocystic acne Acne conglobata is an uncommon form of severe acne. The nodules are usually found on the chest, shoulders, back, buttocks, upper arms and face Figure 8: Acne conglobata Perioral dermatitis. The condition usually occurs in women aged 30 to 45 years Figure 10: Perioral dermatitis Perioral dermatitis. The condition usually occurs in women aged 30 to 45 years Figure 11: Folliculitis Pseudofolliculitis barbae is a sterile condition that is most common in ethnic groups with thick, coarse, curly beard hair Figure 12: Pseudofolliculitis barbae

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