A 6-year-old girl is brought to the office for a round, itchy rash on her body (Figure 123-1). It was first noted 2 weeks ago. The family cat does have some patches of hair loss. Note the concentric rings with scaling, erythema, and central sparing. UV light showed green fluorescence (Microsporum species) and the KOH is positive for branching and septate hyphae. The child was treated with a topical antifungal cream bid and the tinea resolved in 3 to 4 weeks. The family cat was also taken to the veterinarian for treatment.
Tinea corporis on the shoulder of this young girl. This is a very typical annular pattern and the cat on a sweatshirt might be a clue to an infected pet at home spreading a Microsporum dermatophyte to the young girl. Note the concentric rings with scaling, erythema, and central sparing. (Used with permission from Richard P. Usatine, MD.)
Tinea corporis is a common superficial fungal infection of the body, characterized by well-demarcated, annular lesions with central clearing, erythema, and scaling of the periphery.
Dermatophytes are the most prevalent agents causing fungal infections in the US, with Trichophyton rubrum causing the majority of cases of tinea corporis, tinea cruris, tinea manuum, and tinea pedis.
Etiology and Pathophysiology
Tinea corporis is caused by fungal species from any one of the following three dermatophyte genus’: Trichophyton, Microsporum, and Epidermophyton. T. rubrum is the most common causative agent of tinea corporis.
Participation in daycare centers.
Poor personal hygiene.
Living conditions with poor sanitation.
Warm, humid environments.
Conditions that cause weakening of the immune system (e.g., AIDS, cancer, organ transplantation, diabetes).
The diagnosis can be made from history, clinical presentation, culture, and direct microscopic observation of hyphae in infected tissue and hairs after KOH preparation.
Pruritus of affected area.
Well-demarcated, annular lesions with central clearing, erythema, and scaling of the periphery. Concentric rings are highly specific (80%) for tinea infections (Figure 123-1).
Central clearing is not always present (Figure 123-2).
Although scale is the most prominent morphologic characteristic, some tinea infections will actually cause pustules from the inflammatory response (Figure 123-3).
Tinea faciei in a young ...