A case of black dot ringworm attributable to Trichophyton violaceum: a simple method for identifying macroconidia and microconidia formation by Fungi-Tape and MycoPerm-Blue.

An 85-year-old Japanese woman sought a dermatologic consultation for evaluation of a walnut-sized alopecia with pityroid desquamation in the parietal region of her scalp. She had been admitted to a nursing home about three months earlier, and, at that time, a thumb-tip-sized, scaly alopecia was noted. Several hairs at the site were eroded in a black dot. Direct KOH microscopy of affected hair showed large spore endothrix infection. To isolate macro- and microconidia for fungal identification, we incubated the affected hair and scales and obtained giant colonies in a special enriched medium. Using Fungi-tape and MycoPerm-Blue, we were able to collect and identify Trichophyton violaceum macro- and microconidia from the white, powdery, fluffy colony that slowly developed after about six weeks of growth on enriched medium. Over the past 20 years, only about 20 cases of tinea capitis caused by T. violaceum have been reported in Japan, and macroconidia have been identified in only 4 cases, including this one.