A 13 year-old child presents with a lesion on the forearm that is pruritic. What confirms the suspected diagnosis?

The correct choice for confirming the suspected diagnosis in this scenario is the presence of hyphae on a KOH prep. This option is particularly appropriate when considering a pruritic lesion in a child, as it suggests a fungal infection, such as tinea (ringworm). The KOH preparation is a diagnostic test that helps to reveal fungal elements, including hyphae and spores, by clearing away keratin and allowing for direct visualization under a microscope.

In the context of a pruritic lesion, a positive KOH prep would support a diagnosis related to superficial fungal infections. The presence of hyphae indicates active fungal growth, which is essential in confirming tinea when a dermatophyte infection is suspected.

Other diagnostic methods mentioned may provide useful information but do not specifically confirm a diagnosis of a pruritic lesion in this age group as directly as the KOH prep for fungal infections. For instance, a patch test is generally used to identify contact dermatitis due to allergens, which is less likely in this scenario. Gram staining of skin lesions would be more relevant in cases of suspected bacterial infections rather than pruritic dermatoses. The Tzanck smear is used primarily in the diagnosis of herpes virus infections but isn’t typically associated with diagnosing