Occupational Acne

Occupational acne is an acneiform eruption of hair follicles caused or aggravated by workplace exposure to oils, tars, halogenated hydrocarbons, or friction and occlusion. It is a group of related conditions rather than one disease.

Types. Oil acne from cutting and lubricating oils, chloracne from halogenated aromatic compounds, tar acne from coal tar, pitch and creosote, and acne mechanica from friction, pressure and occlusion (helmets, masks, straps). Heat, humidity and occlusive clothing also aggravate pre-existing acne.

Epidemiology. Machinists, mechanics, refinery and chemical workers, roofers, road workers and people wearing protective clothing in hot environments are most affected. It is commoner in men and often starts later than adolescent acne.

Distinguishing features. Lesions follow the sites of contact (forearms, thighs, face, skin under occlusive clothing). Comedones predominate, and the distribution differs from usual acne.

Course. It usually improves when exposure stops. Chloracne may persist for years.

Pathophysiology.

Oils and tars occlude follicular openings and promote follicular hyperkeratosis, producing comedones. Colonisation with Cutibacterium acnes and inflammation follow.

Halogenated aromatic compounds act through the aryl hydrocarbon receptor and transform sebaceous glands into keratinising cells. Friction, heat and occlusion add follicular obstruction and rupture.

• Open and closed comedones, papules and pustules at contact sites, with scarring in chronic disease.
• Nodules and cysts in severe or halogenated hydrocarbon disease.
• Often little itch; itch suggests coexisting contact dermatitis.

Red flags.

• Extensive cysts with jaundice, weight loss or neuropathy (systemic halogenated hydrocarbon toxicity).
• Spreading redness, pus or fever (secondary infection).
• New warty, ulcerated or non-healing lesion on oil or tar exposed skin (skin cancer).

• Exposure history: agents, contact route, clothing, skin cleaning methods and effect of time away from work.
• Examination of distribution, with attention to sites outside the usual acne areas.
• Skin swab for pustules; patch testing when dermatitis coexists.
• Suspected halogenated hydrocarbon exposure: liver enzymes, fasting lipids, urinary porphyrins and specialist serum assay.
• Women with hirsutism or irregular menses: assess for polycystic ovary syndrome and androgen excess.

Differential diagnosis. Acne vulgaris, bacterial or Malassezia folliculitis, rosacea, steroid acne, drug induced acneiform eruption (corticosteroids, lithium, phenytoin, anabolic steroids, EGFR inhibitors), keratosis pilaris, hidradenitis suppurativa, tinea.

• Control exposure: enclosed machines and splash guards, daily clean overalls, prompt change of oil soaked clothing, washing after the shift with mild soap, no solvents or abrasives on skin, and padding to reduce friction.
• Adapalene 0.1% gel topically once daily at night to affected areas, long term. Start every second night if irritated. Maximum one thin application daily. Monitor irritation and photosensitivity. Avoid in pregnancy; no renal or hepatic adjustment.
• Benzoyl peroxide 5% gel topically once daily in the morning for up to 12 weeks, then review. Maximum twice daily. Monitor irritation and bleaching of fabrics. No renal adjustment.
• Doxycycline 100 mg orally once daily with food and a full glass of water for up to 12 weeks for inflammatory lesions. Maximum 100 mg daily. Monitor photosensitivity, oesophagitis and headache or visual change. Avoid in pregnancy, breastfeeding and under 12 years; no renal adjustment; caution in hepatic impairment.
• Severe, nodular or scarring disease: isotretinoin orally 0.5 mg/kg daily with food for 4 weeks, then 0.5 to 1 mg/kg daily to a cumulative dose of 120 to 150 mg/kg. Maximum 1 mg/kg daily. Monitor liver enzymes and fasting lipids at baseline, at 1 month and every 3 months, a monthly pregnancy test, and mood. Contraindicated in pregnancy and breastfeeding, hepatic impairment, uncontrolled hyperlipidaemia, and with tetracyclines. In severe renal impairment start at 10 mg daily and increase as tolerated. Specialist use only.
• Comedone extraction and drainage by a clinician; treat secondary infection by swab result.

Monitoring. Review at 6 to 8 weeks, then every 3 months until clear; reassess exposure at each visit.

Referral and escalation. Dermatology for nodular, scarring or refractory disease; occupational physician for workplace change; urgent review for any suspicious skin lesion; notification and compensation where required.

Special groups. Pregnancy: avoid retinoids and tetracyclines; topical benzoyl peroxide is acceptable. Women of childbearing potential on isotretinoin need effective contraception from 1 month before to 1 month after treatment.