Buruli ulcer — DTM&H MCQ

Correct answer: D — Buruli ulcer

Buruli ulcer (D) is correct because a painless ulcer with undermined edges, a necrotic base and minimal surrounding inflammation in a child from rural West Africa is the classic description of Mycobacterium ulcerans infection. The organism produces mycolactone, a toxin that causes tissue necrosis while simultaneously suppressing the local immune response and destroying peripheral nerve fibres, which explains the striking lack of pain and inflammation despite extensive tissue destruction. Ghana is a recognised endemic focus, and children in rural riverine or wetland areas are the group most commonly affected. The undermined, sloughy necrotic base is a specific clinical hallmark used for presumptive diagnosis in endemic settings before laboratory confirmation. Why the other options are wrong: A. Cutaneous leishmaniasis: typically produces a painless nodule or crusted ulcer with a raised, indurated border rather than undermined edges, and is transmitted by sandflies in different endemic zones, not classically rural Ghana. B. Yaws: causes papillomatous or ulcerative lesions (mother yaw) with a raspberry-like granulomatous surface, not a necrotic undermined base, and is caused by Treponema pallidum subspecies pertenue. C. Mycetoma: presents as a chronic, slowly progressive, painless swelling with multiple sinuses discharging grains, usually on the foot, rather than a single undermined necrotic ulcer. E. Tropical ulcer: is typically acutely painful, rapidly enlarging, with a purulent, foul-smelling base and surrounding inflammation, the opposite of the minimally inflamed, painless picture described. Key point: painless, undermined, necrotic-based ulcer in a child from an endemic African wetland area is the classic mycolactone-driven presentation of Buruli ulcer (Mycobacterium ulcerans).

Reference: World Health Organization, Buruli ulcer (Mycobacterium ulcerans infection) fact sheet, https://www.who.int/news-room/fact-sheets/detail/buruli-ulcer-(mycobacterium-ulcerans-infection)