Dr Ivana Chim ( left ) Dermatology research fellow at Sinclair Dermatology , East Melbourne , Victoria .

Dr Samantha Eisman ( right ) Consultant dermatologist and clinical trial investigator at Sinclair Dermatology , East Melbourne , Victoria .

First published online on 17 November 2023

INTRODUCTION

ACNE vulgaris is a common presentation

in both general practice and specialist dermatologist clinics . It is characterised by the development of comedones , papules , pustules and / or nodules , and is driven by a myriad of underlying factors . Acne occurs most commonly in preadolescents and adolescents , with the estimated prevalence peaking at 93.3 % in Australian 16-18 year olds ; a significant decrease in prevalence is seen after the third decade of life . 1 , 2 However , acne can present in all age groups , and has a variable course and disease severity . The disease itself may cause significant social embarrassment and psychological distress , and its sequelae may be permanently disfiguring . 3

This How to Treat aims to cover the underlying factors driving acne production , describe common acne presentations , and provide practical approaches to treatment and when to seek specialist opinion .

PATHOGENESIS AND ASSOCIATED DISEASES

THE pilosebaceous unit comprises

a hair follicle and sebaceous gland .

Build-up of debris from follicular keratinisation and excess sebum in these units form closed comedones , often referred to as ‘ whiteheads ’. As more keratinocytes accumulate and the sebum oxidises , the lesions enlarge and evolve into open comedones , known as ‘ blackheads ’. Finally , inflammation in response to commensal skin pathogens , such as Cutibacterium acnes ( formerly known as Proprionibacterium acnes ), transforms the lesions into papules and pustules . Rupture of these lesions , and subsequent spread of bacteria and pro-inflammatory materials , contributes to nodule formation and exacerbates inflammation . 4

It is commonly thought that excess sebum is a key driver in the development of acne vulgaris . This is supported by an increased incidence of acne in preadolescence and adolescence because of increased androgen production . Androgens stimulate both the growth and secretory functions of sebaceous glands , resulting in increased sebum production . 5 Hormone-sensitive sebaceous glands are present on the face and neck , chest , upper back and upper limbs . The increased sebum production

promotes an environment for C . acnes , the predominant commensal pathogen in the pilosebaceous follicle , to propagate . C . acnes not only activates innate and adaptive immune responses that drive inflammatory acne , but also forms a biofilm within follicles that restricts sebum drainage and possibly contributes to antibiotic resistance . 4

Persistent acne vulgaris is commonly associated with diseases resulting in hyperandrogenism . Conditions associated with hyperandrogenism include polycystic ovary syndrome ( PCOS ), congenital adrenal hyperplasia and adrenal or ovarian tumours . The prevalence of PCOS in Australian women of reproductive age is 8-13 %. 6 Screen for PCOS in women who present with associated features of hirsutism , irregular menses or oligomenorrhoea , and / or large body habitus , or resistant acne poorly responsive to treatment . Pregnancy , with its fluctuating increase in androgen hormones , can also be associated with worsening of acne . 7

In the subset of patients who experience adult acne past their third decade , women are much more commonly affected than men , with an

estimated prevalence of 12-54 %. 8 This may be as a result of persistent acne from young adulthood , a recurrence of previous acne , or new late-onset acne , a phenomenon that has been reported in up to 20-40 % of women . 8 Adult female acne is typically distributed about the lower face , although other areas may be affected ; this distribution may differentiate it from rosacea that typically occurs in the mid-facial region .

Although PCOS may be one of the leading contributors to adult female acne , other hormonal and lifestyle factors may play a role . Possible contributors to the development of acne include stress , diet , in particular dairy and high glycaemic intake , a family history of acne , and a high BMI . 9-12 However , there is currently a lack of high-grade literature available to support these theories . There is a dearth of evidence regarding the optimal diet for acne , and the efficacy of vitamin supplementation .

PRESENTATION AND SEVERITY

THE presentation ( see box 1 ) and severity

, including the distribution and degree of skin involvement , with