Tinea capitis caused by Trichophyton tonsurans presenting as an obscure patchy hair loss due to daily antifungal shampoo use

The document reports a case of a 38-year-old female primary school teacher with a history of asymptomatic, bizarre-shaped, non-scarring alopecia for several years, who had been using over-the-counter ketoconazole shampoo regularly. Initial tests, including a potassium hydroxide (KOH) preparation, were negative for fungal organisms. However, a scalp biopsy revealed an endothrix infection, and dermoscopic examination showed signs consistent with tinea capitis, such as comma hair and corkscrew hair. The fungal culture confirmed the presence of Trichophyton tonsurans. The study suggests that the daily use of antifungal shampoo may have concealed the clinical and laboratory findings, making diagnosis difficult. The patient was eventually treated with griseofulvin and ketoconazole shampoo, leading to a complete clinical cure. The case highlights the importance of high clinical suspicion and the use of histopathology and dermoscopic examinations for the diagnosis of T. tonsurans tinea capitis, especially when initial tests are negative and the presentation is atypical.