MCQ of the Day: 13 November 2026

Answer: B. Sporothrix schenckii. Sporotrichosis ("rose gardener's disease") follows traumatic inoculation of soil or plant material, typically by a thorn. The classic picture is lymphocutaneous: a painless papule or ulcer at the inoculation site, followed by a chain of nodules along the draining lymphatics. S. schenckii is thermally dimorphic. At 25 °C it is a mould whose colonies darken from cream to brown-black, with delicate septate hyphae and conidia clustered in a flower-like (rosette) pattern. At 37 °C, and in tissue, it forms small cigar-shaped budding yeasts. Asteroid bodies (yeast surrounded by radiating eosinophilic material, the Splendore-Hoeppli phenomenon) support the diagnosis. Itraconazole is the usual first-line treatment.

A. Nocardia brasiliensis can also cause lymphocutaneous infection, but it is a branching, filamentous, partially acid-fast bacterium, not a dimorphic fungus.

C. Histoplasma capsulatum is dimorphic, but its mould phase has tuberculate macroconidia, and its tissue phase is small oval yeasts inside macrophages; it mainly causes pulmonary or disseminated disease.

D. Fonsecaea pedrosoi is a pigmented mould that is not dimorphic; chromoblastomycosis shows sclerotic (Medlar) bodies in verrucous lesions.