Microsporum nanum was first described in 1954 by Fuentes, Aboulafia, and Vidal,1 who isolated a "dwarf form" of Microsporum gypseum from a case of tinea capitis (kerion) in an 8-year-old white boy. They classified this organism as M. gypseum var. nanum. Seven months later these same investigators1 isolated a similar strain from a glabrous skin infection in an adult. In 1956 Fuentes2 reported that the 2 isolates previously described had proved to be stable in their gross and microscopic characteristics over a period of 3 years. He then proposed that this organism be considered a new species: Microsporum nanum. Ajello3 now classifies M. nanum as a separate species of Microsporum.
The initial case reported by Fuentes et al.1 presented the following findings: 1. The lesion was a kerion. 2. The fungus invaded hair as an endothrix. 3. Infected hairs exposed to Wood's light fluoresced with
BROCK JM. Microsporum Nanum: A Cause of Tinea Capitis: A Case Report. Arch Dermatol. 1961;84(3):504–505. doi:10.1001/archderm.1961.01580150150027
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