Acne is usually recognized as a disorder of adolescence. However, the referral of patients over the age of 25 years with acne has significantly increased over the past 10 years. The clinical features of 200 patients over the age of 25 years, referred to our department for treatment of acne, were evaluated with a view to establishing possible aetiological factors. There were 152 (76%) women and 48 (24%) men. The mean age of the patients was 35.5 years (range 25-55 years). The acne was mild or moderate in severity, consisting principally of inflammatory lesions, with mean total acne grade (Leeds Grading Scale) of 1.125 for men and 0.75 for women. Most patients had persistent acne; but true late-onset acne (onset after the age of 25 years) was seen in 28 (18.4%) of women and four (8.3%) of men. Thirty-seven per cent of women had features of hyperandrogenicity. One hundred and sixty-four patients (82%) had failed to respond to multiple courses of antibiotics, and 64 (32%) had relapsed after treatment with one or more courses of isotretinoin. External factors, such as cosmetics, drugs and occupation, were not found to be significant aetiological factors. A family history revealed that 100 (50%) of patients had a first-degree relative with post-adolescent acne. Patients with post-adolescent acne appear to represent an increasingly important population of acne sufferers. External factors do not seem to have a significant aetiological role. Two main clinical groups were identified: those with persistent acne and those with late-onset acne. A minority of women also had features of hyperandrogenicity. These patients, and those with late-onset acne, may represent a subgroup who have underlying abnormalities of ovarian, adrenal or local androgen metabolism, and require separate investigation.

Acne is usually recognized as a disorder of adolescence. However, the referral of patients over the age of 25 years with acne has significantly increased over the past 10 years. The clinical features of 200 patients over the age of 25 years, referred to our department for treatment of acne, were evaluated with a view to establishing possible aetiological factors. There were 152 (76%) women and 48 (24%) men. The mean age of the patients was 35.5 years (range 25-55 years). The acne was mild or moderate in severity, consisting principally of inflammatory lesions, with mean total acne grade (Leeds Grading Scale) of 1.125 for men and 0.75 for women. Most patients had persistent acne; but true late-onset acne (onset after the age of 25 years) was seen in 28 (18.4%) of women and four (8.3%) of men. Thirty-seven per cent of women had features of hyperandrogenicity. One hundred and sixty-four patients (82%) had failed to respond to multiple courses of antibiotics, and 64 (32%) had relapsed after treatment with one or more courses of isotretinoin. External factors, such as cosmetics, drugs and occupation, were not found to be significant aetiological factors. A family history revealed that 100 (50%) of patients had a first-degree relative with post-adolescent acne. Patients with post-adolescent acne appear to represent an increasingly important population of acne sufferers. External factors do not seem to have a significant aetiological role. Two main clinical groups were identified: those with persistent acne and those with late-onset acne. A minority of women also had features of hyperandrogenicity. These patients, and those with late-onset acne, may represent a subgroup who have underlying abnormalities of ovarian, adrenal or local androgen metabolism, and require separate investigation.

The pattern of presenting dermatitis in children should not determine referral for patch testing. Any child with persistent eczema should be referred for patch testing.

Hypercornification is an early feature of acne and precedes inflammation. It is associated with ductal hyperproliferation and there are many controlling factors such as androgens, retinoids and cytokines. Cycling of normal follicles and of comedones may explain the natural resolution of comedones and, in the longer term, resolution of the disease itself. There is a need to tailor treatment according to comedonal type. Suboptimal therapy can often result from inappropriate assessments of comedones, especially microcomedones, missed comedones, sandpaper comedones, submarine comedones and macrocomedones. Macrocomedones can produce devastating acne flares, particularly if patients are inappropriately prescribed oral isotretinoin. Gentle cautery under topical local anaesthesia is a useful therapy in the treatment of such lesions. The newer retinoids and new formulations of all-trans-retinoic acid show a better benefit/risk ratio. Evidence-based studies are required to allow adequate comparisons.

Adults with acne represent an increasingly important population of acne sufferers referred for treatment. Acne, in these patients, is generally mild or moderate in severity but tends to be resistant to conventional antibiotic therapy. A study was carried out to assess the efficacy of intermittent moderate dose isotretinoin as a treatment for acne. Eighty consecutive patients, over the age of 25 years, referred with acne unresponsive to, or relapsing rapidly after three or more courses of conventional antibiotic therapy were recruited. Acne severity was assessed on the face, chest and back using the Leeds grading scale and the number of inflamed lesions was counted at the site showing the highest acne grade. The patients were 22 men and 58 women. The treatment regimen consisted of isotretinoin, 0.5 mg/kg per day for 1 week in every 4 week for a total period of 6 months. Seventy-five patients completed the study. The therapy was very well tolerated with mild cheilitis as the only side-effect. At the end of treatment, both total acne grade and lesion counts were significantly reduced (P < 0.0001). The acne had resolved in 68 (88%) patients. Twelve months after treatment, acne grades and inflamed lesion counts remained significantly improved (P < 0.0001) in the 68 patients who responded; however, 26 (39%) patients had relapsed. There was a significantly higher incidence of relapse in patients with predominantly truncal acne (P = 0.01). Patients who relapsed also had a significantly higher total acne grade, lesion count (P < 0.0001) and sebum excretion rate (P < 0.001) compared with those whose acne resolved. This study suggests that intermittent moderate dose isotretinoin may be a cost-effective alternative to full dose isotretinoin in a carefully selected group of adult patients with-acne. Selection criteria should include predominantly facial acne, total acne grade less than 1, inflamed lesion count less than 20 and sebum excretion rate less than 1.25 micrograms/cm2 per min.