Chronic <i>Trichophyton indotineae</i> Infections Mimicking Adult-Onset Atopic Dermatitis

Tricophyton indotineae is a dermatophyte endemic to South Asia that has been increasingly prevalent in the United States. Its atypical appearance and resemblance to atopic dermatitis (AD), clinically and histologically, has resulted in misdiagnosis and mismanagement. It is associated with multidrug resistance which complicates treatment when mismanaged. We were presented with two cases of chronic T.indotineae infections that were being treated as adult-onset AD with topical steroids and immune modulators without resolution. A punch biopsy and fungal culture confirmed T.indotineae and antifungal therapy was initiated. The clinical similarity between AD and T. Indotineae can lead to mistreatment, a prolonged infection course with the potential to spread, and hardship on the patient. To be thorough in a treatment-resistant AD profile, a skin biopsy, targeted laboratory tests, microscopic examination, and a KOH preparation may be indicated. Additionally, social history including travel to endemic areas is important. These measures may decrease inappropriate treatment as AD treatments are ineffective for T. Indotineae and often make it worse. Clinicians should consider T. indotineae in cases of presumed adult-onset or refractory AD that lacks personal or family history of atopy or fail improvement after adequate trials of standard AD therapies. Early performance of a punch biopsy combined with fungal culture is the gold standard for diagnosis. These cases highlight the importance of understanding dermatophyte epidemiology with increasing travel.