Acne Conglobata

Acne conglobata is a severe, chronic, scarring form of acne with large inflammatory nodules, abscesses, interconnecting sinus tracts and double ended comedones. It mainly involves the trunk, buttocks, upper arms and thighs, and the face is often spared or less affected.

It affects mostly young men from age 18 to 30, and persists for years if untreated. It is rare compared with acne vulgaris. It forms part of the follicular occlusion spectrum with hidradenitis suppurativa, dissecting cellulitis of the scalp and pilonidal sinus.

Triggers include anabolic steroids, testosterone, androgen secreting tumours, halogens and chronic bacterial colonisation. It may start in a person with previous moderate acne and can follow a sudden flare. There is a genetic susceptibility.

Pathophysiology.

Follicular occlusion with keratin and sebum, colonisation with Cutibacterium acnes and a strong innate immune response lead to rupture of the follicle, deep abscesses and sinus tracts. Androgenic stimulation of sebaceous glands increases sebum production and follicular plugging.

• Many comedones, including double ended and multiple headed comedones, with deep tender nodules and abscesses.
• Interconnecting sinuses that drain pus or blood stained material, healing with keloid, atrophic and bridged scars.
• Distribution on the chest, back, shoulders, buttocks and thighs, with a less severe face.
• Pain, odour and psychological distress. Systemic symptoms are absent, unlike acne fulminans.

Red flags.

• Fever, arthralgia or ulcerating lesions, suggesting acne fulminans.
• Virilisation, menstrual disturbance or hirsutism, suggesting androgen excess.
• Anabolic steroid or testosterone use.

• Clinical diagnosis from the nodular, sinus forming pattern.
• Swab of discharge for bacteria and culture if suppurative disease is suspected.
• In people with signs of androgen excess: total and free testosterone, dehydroepiandrosterone sulphate, sex hormone binding globulin, luteinising hormone, follicle stimulating hormone, 17-hydroxyprogesterone and prolactin.
• Before isotretinoin: pregnancy test, fasting lipids, liver tests and full blood count.
• Review for hidradenitis suppurativa, pilonidal disease and scalp involvement.

Differential diagnosis. Acne fulminans, hidradenitis suppurativa, acne vulgaris, steroid acne, bacterial or Gram negative folliculitis, furunculosis, pseudofolliculitis, deep fungal infection and pyoderma.

First line.

• Isotretinoin 0.5 mg/kg/day for the first 4 weeks (starting at 0.25 mg/kg/day if there is a risk of flare), then 0.5 to 1 mg/kg/day, to a cumulative dose of 120 to 150 mg/kg. Take with food.
• Isotretinoin is teratogenic. Women of childbearing potential must use reliable contraception for 1 month before, during and for 1 month after treatment, with monthly pregnancy tests.
• Monitor lipids and liver tests at baseline, at 4 to 8 weeks and then as needed. Ask about mood at each visit, and about dry lips, dry eyes and musculoskeletal pain. Avoid tetracyclines during isotretinoin.

Adjuncts.

• Doxycycline 100 mg twice daily (or lymecycline 408 mg daily) for the first 4 to 8 weeks to reduce flare, then stop.
• Prednisolone 0.5 mg/kg/day for 2 to 4 weeks, tapered, if a severe flare occurs at the start of isotretinoin.
• Intralesional triamcinolone acetonide 2.5 to 5 mg/mL for isolated nodules, in small volumes to avoid atrophy.
• Stop anabolic steroids and other triggering agents.

Scarring. Treat scars after control, with laser, subcision, fillers or surgery. Early treatment limits scarring.

Monitoring. Review monthly during isotretinoin. After treatment, review at 3 and 6 months for relapse, since relapse needs a repeat course.

Referral and escalation. Refer to dermatology for diagnosis, isotretinoin, and when sinus tracts or fever suggest complications.

Special groups. Isotretinoin is absolutely contraindicated in pregnancy and breastfeeding. Avoid in untreated depression.