Ans. C: Trichophyton Tinea cruris, a pruritic superficial fungal infection of the groin and adjacent skin, is the second most common clinical presentation for dermatophytosis The most common etiologic agents for tinea cruris include Trichophyton rubrum and Epidermophyton floccosum; less commonly Trichophyton mentagrophytes and Trichophyton verrucosum are involved. Tinea cruris is a contagious infection transmitted by fomites, such as contaminated towels or hotel bedroom sheets, or by autoinoculation from a reservoir on the hands or feet (tinea manuum, tinea pedis, tinea unguium). The etiologic agents in tinea cruris produce keratinases, which allow invasion of the cornified cell layer of the epidermis. Findings includes: Large patches of erythema with central clearing are centered on the inguinal creases and extend distally down the medial aspects of the thighs and proximally to the lower abdomen and pubic area. Scale is demarcated sharply at the periphery. In acute tinea cruris infections, the rash may be moist and exudative. Chronic infections typically are dry with a papular annular or arciform border and barely perceptible scale at the margin. Central areas typically are hyperpigmented and contain a scattering of erythematous papules and a little scale. Malassezia furfur is implicated in pityriasis versicolor and malassezia folliculitis.