Follicular skin diseases
Acne case challenge 1
A 16-year-old girl presents with acne affecting her face. The forehead is the worst affected area.
In case 1, which of the following skin lesions are clinically apparent?
#! Erythematous papules || A small palpable lesion less than 0.5 cm diameter. They are raised above the skin surface, and may be solitary or multiple.
# Nodules || An enlargement of a papule in three dimensions (height, width, length). It is a solid lesion.
#! Comedones || Technical term for blackhead / whitehead (uninflamed acne lesion)
#! Pustules || A purulent vesicle. Filled with neutrophils. May be white or yellow.
Explanation: She has comedones, papules and pustules on the forehead. There are no nodules.
She tells you she has used several products on her spots from time to time during the last six months. “None of them work!”
Which one is least likely to have been helpful?
*! Aqueous cream
* Benzoyl peroxide 5% cream
* Face wash containing triclosan
* Blemish cover stick containing sulphur
Explanation: Moisturisers such as aqueous cream may be occlusive and aggravate acne. She has used other products that contain ingredients known to be helpful for acne. However, they are more effective if used consistently once or twice daily to all areas affected rather than to individual spots.
Which of the following topical medications might you prescribe for her?
#! Tretinoin cream
#! Isotretinoin gel
# Metronidazole gel
#! Adapalene gel
Explanation: Topical retinoids require a prescription. The three available in New Zealand are tretinoin, isotretinoin and adapalene. Metronidazole is used to treat rosacea, but also requires prescription.
She informs you she has “sensitive skin”. Which of the following diagnoses are possible?
#! Contact allergic dermatitis
#! Contact irritant dermatitis
#! Atopic dermatitis
#! Seborrhoeic dermatitis
Explanation: She may mean any of the suggested options as well as non-specific stinging and burning on applying topical agents. To distinguish them, obtain a detailed history and examine the skin. Unfortunately topical anti-acne agents may be poorly tolerated.
What advice would you give in relation to the topical retinoid you have prescribed?
# Apply twice daily to get used to it as quickly as possible
#! Start alternate nights and slowly build up to twice daily if and as tolerated
# Test a small area and apply the cream to this site four times daily for 5 days
#! Use a little oil-free moisturiser if treated areas become red and dry
Explanation: As well as the correct options, advise her: to stay out of the sun, and / or apply an oil-free sunscreen; to avoid using any additional anti-acne products; wash once or twice daily with gentle soap-free and medication-free cleanser; return for review if the medication is not tolerated at least three times weekly. You should ensure she is not pregnant, and that she is using adequate contraceptive precautions if sexually active.
Explanation: If she is unable to tolerate the retinoid, suggest she uses an aqueous formulation of benzoyl peroxide 2.5% or azelaic acid cream.
She doesn’t have any known drug allergies. Which of the following oral medications might be suitable first line agents?
* Doxycycline 50mg daily for 2 weeks
*! Minocycline 50mg bd for 12 weeks
* Co-trimoxasole 80mg/400mg bd for 12 weeks
* Ethynodiol diacetate 500µg daily
Explanation: Doxycycline and minocycline are tetracycline antibiotics suitable for acne treatment. The usual dose of doxycycline is 100mg daily (range 50- 200mg). However, improvement is not likely to be evident prior to at least 4 to 6 weeks, and acne treatment should be continued for at least 3 to 6 months. Co-trimoxasole is a useful second-line antibiotic for severe inflammatory acne, but has a higher incidence of serious adverse effects than the tetracycline group. Ethinodiol diacetate is a progestogen-only contraceptive and is not useful for treatment; in fact it may provoke acne in some women. Instead, consider a second-generation combined agent or ethinyloestrodiol / cyproterone.
When should you arrange to review?
* Two weeks
*! Three months
* Six months
* It’s up to the patient
Explanation: Three-month follow-up is recommended as this emphasises to the patient to persist with treatment and gives it long enough to be visibly effective. However, the patient should return to see you earlier if there is an adverse event or the acne becomes significantly more severe.