Eumycetoma — DTM&H MCQ

Correct answer: A — Eumycetoma

The correct answer is A, Eumycetoma. The clinical picture of a painless, slow-growing subcutaneous mass with discharging granules over years is classic mycetoma (Madura foot), and histology showing the Splendore-Hoeppli phenomenon (eosinophilic, radiating material encasing the fungal grain, an immune reaction to a large antigenic focus) together with broad, thick-walled fungal hyphae within the grain points specifically to a fungal (eumycotic) rather than bacterial (actinomycotic) aetiology. Madurella mycetomatis is the commonest cause of eumycetoma in Senegal and across the African mycetoma belt, fitting the geographic history given. Actinomycete grains contain thin, delicate filaments and typically provoke a Splendore-Hoeppli reaction less prominently and with a different histological texture, so the described histology discriminates fungal from bacterial disease rather than grain colour alone, which is an unreliable sole discriminator. Why the other options are wrong: E. Cutaneous tuberculosis: presents with lupus vulgaris, scrofuloderma or verrucous plaques, not discharging granules; histology shows caseating granulomas with Langhans giant cells, not Splendore-Hoeppli grains. D. Chromoblastomycosis: causes verrucous, cauliflower-like plaques with characteristic copper-coloured sclerotic (Medlar) bodies on histology, not discharging grains with Splendore-Hoeppli phenomenon. B. Actinomycetoma: caused by filamentous bacteria (Nocardia, Actinomadura, Streptomyces species); grains show thin bacterial filaments on Gram stain rather than the broad septate fungal hyphae seen here, and the disease responds to prolonged antibiotics rather than antifungals. C. Subcutaneous phycomycosis: caused by Basidiobolus, produces a firm, movable subcutaneous swelling without sinus tracts or grain discharge, and histology shows eosinophilic infiltrate around broad aseptate hyphae, not a mycetoma grain with Splendore-Hoeppli change. Key point: Splendore-Hoeppli phenomenon around a grain containing broad, thick-walled hyphae confirms fungal (eu-) mycetoma, distinguishing it histologically from the thin bacterial filaments of actinomycetoma.

Reference: WHO Fact Sheet, Mycetoma, and WHO Target Product Profile for a rapid diagnostic test for mycetoma (2022): eumycetoma agents (e.g. Madurella mycetomatis) form fungal grains distinguished histologically by broad septate hyphae and Splendore-Hoeppli reaction, versus thin bacterial filaments in actinomycetoma. https://www.who.int/publications/i/item/9789240047075