Anthrax cutaneous disease — DTM&H MCQ

Correct answer: E — Cutaneous anthrax

Cutaneous anthrax (option B) is correct because the classic occupational triad, a painless papule progressing to a black eschar with striking surrounding oedema, in a worker exposed to animal hides, is pathognomonic for Bacillus anthracis skin infection. Spores from contaminated hides, wool or hair enter through a break in the skin and germinate locally, producing oedema toxin and lethal toxin, which drive the marked, gelatinous, non-pitting oedema disproportionate to the size of the lesion. Historically termed the malignant pustule of tanners and wool-sorters, this presentation is a recognised occupational hazard in leather and hide handlers, and anthrax is a notifiable disease in the UK requiring urgent reporting to the local UKHSA health protection team. Painlessness despite tissue destruction is the key clinical clue distinguishing it from most other ulcerating skin infections. Why the other options are wrong: C. Plague: Yersinia pestis causes painful buboes with fever and systemic toxicity, typically after flea bites or contact with rodents, not painless eschars from hide handling. D. Orf: This is a parapoxvirus infection from sheep or goats causing a painful or itchy nodular lesion, usually on the fingers, without the extensive brawny oedema or black eschar of anthrax. B. Leishmaniasis: Cutaneous leishmaniasis produces a slowly evolving painless ulcer following sandfly bites, with a much longer indolent course and no history of hide exposure or marked surrounding oedema. A. Scrub typhus: Caused by Orientia tsutsugamushi transmitted by chigger mites, it produces a small eschar (tache noire) but is accompanied by fever, lymphadenopathy and a rash, and is linked to scrub vegetation exposure, not tannery work. Key point: A painless black eschar with disproportionate surrounding oedema in someone handling hides, wool or animal hair is the classic occupational presentation of cutaneous anthrax.

Reference: Patient.info Professional (GP resource), Anthrax, UK notifiable disease guidance; UKHSA notifiable diseases reporting requirements, gov.uk