Hidradenitis suppurativa — RACGP Fellowship MCQ

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HardDermatologyHidradenitis suppurativaRACGP Fellowship

A 38-year-old woman has recurrent painful nodules and abscesses in both axillae with sinus tracts and scarring. She smokes and has BMI 34 kg/m². Swabs have repeatedly shown mixed skin flora. What is the most likely diagnosis?

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Correct answer: C — Hidradenitis suppurativa

Explanation lettering: D = shown as A · C = shown as B · B = shown as C · A = shown as D

The answer is B: Hidradenitis suppurativa. This patient meets modified Dessau criteria: recurrent painful nodules progressing to abscesses with sinus tracts and scarring in the bilateral axillae (a classic intertriginous site). The demographic profile—female, obese (BMI 34), smoker—aligns with established HS risk factors. Mixed skin flora on swabs is consistent with secondary colonisation of HS lesions; the disease is fundamentally inflammatory, not infectious. Folliculitis (A) causes superficial pustules without sinus tracts or severe scarring. Cutaneous TB (C) would show acid-fast bacilli, not mixed flora, and has a different morphology. Atopic dermatitis (D) presents with lichenification and pruritus, not nodules, abscesses, or sinus tracts. Scabies (E) causes burrows and intense itch, self-limits, and does not form deep scars.

Reference: Australasian hidradenitis suppurativa management guidelines. Australasian Society for Dermatologic Surgery. 2024. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11898165/