Tinea incognita

A dermatological condition caused by fungal infection

Tinea incognita is a dermatological condition characterized by a fungal infection that presents atypically due to the use of topical immunosuppressive agents, such as corticosteroids. This condition is often misdiagnosed because the typical inflammatory response is suppressed, leading to a less obvious clinical presentation.

Pathophysiology

Tinea incognita on the forearm

Tinea incognita occurs when a dermatophyte infection is altered by the application of topical corticosteroids or other immunosuppressive treatments. These agents reduce the body's inflammatory response, which can mask the typical signs of a fungal infection, such as redness, scaling, and itching. As a result, the infection may spread more extensively before being correctly identified.

Clinical Presentation

The clinical presentation of tinea incognita can vary significantly, making diagnosis challenging. Common features include:

• Atypical Lesions: The lesions may appear less inflamed and more subtle than typical tinea infections.
• Color Changes: The affected skin may show unusual pigmentation, often appearing hypopigmented or hyperpigmented.
• Minimal Scaling: Unlike classic tinea infections, scaling may be minimal or absent.
• Widespread Distribution: The infection may cover a larger area due to delayed diagnosis and treatment.

Diagnosis

Diagnosis of tinea incognita requires a high index of suspicion, especially in patients with a history of topical steroid use. Diagnostic methods include:

• KOH Preparation: A potassium hydroxide (KOH) preparation of skin scrapings can reveal fungal elements.
• Fungal Culture: Culturing the organism can confirm the diagnosis and identify the specific dermatophyte.
• Skin Biopsy: In some cases, a skin biopsy may be necessary to differentiate from other dermatoses.

Treatment

The primary treatment for tinea incognita involves discontinuing the use of topical corticosteroids and initiating antifungal therapy. Options include:

• Topical Antifungals: Such as clotrimazole or terbinafine.
• Oral Antifungals: In extensive cases, oral antifungals like itraconazole or fluconazole may be required.

Prevention

Preventing tinea incognita involves careful use of topical corticosteroids, particularly in patients with a history of fungal infections. Educating patients about the potential risks of self-medicating with steroids is crucial.

Related pages

• Dermatophyte
• Tinea
• Corticosteroid
• Fungal infection