Diagnosis: Tinea corporis
The KOH preparation was positive for hyphae in 4 separate sites (trunk, left arm, left leg, and left neck), confirming the diagnosis of severe extensive tinea corporis (FIGURE 2).
Dermatophyte (tinea) infections are caused by fungi that invade and reproduce in the skin, hair, and nails. Dermatophytes, which include the genera Trichophyton, Microsporum, and Epidermophyton, are the most common cause of superficial mycotic infections. As of 2016, the worldwide prevalence of superficial mycotic infections was 20% to 25%.1 Tinea corporis can result from contact with people, animals, or soil. Infections resulting from animal-to-human contact are often transmitted by domestic animals. In this case, the patient’s exposure was from her new cat.
Tinea corporis classically manifests as pruritic, erythematous patches or plaques with central clearing, giving it an annular appearance. The response to a tinea infection depends on the immune system of the host and can range in severity from superficial to severe.2 There are 2 forms of severe dermatophytosis: invasive, which involves localized perifollicular sites or deep dermatophytosis, and extensive, which is confined to the stratum corneum but results in numerous lesions.3
The diagnosis of tinea corporis is commonly confirmed using direct microscopic examination with 10% to 20% KOH preparation, which will show branching and septate hyphal filaments.4
Several conditions with annular lesions comprise the differential
The findings of pruritic annular erythematous lesions on the patient’s neck, chest, trunk, and bilateral extremities led the patient to suspect this was a worsening case of her guttate psoriasis. Other possible diagnoses included pityriasis rosea, subacute cutaneous lupus erythematosus (SCLE), and secondary syphilis.
Continue to: Guttate psoriasis