Which of the following is a risk factor for tinea cruris?

• A. Increased skin moisture
• B. Immunodeficiency (HIV, DM)
• C. Hypothyroidism
• D. Frequent sunscreen use

Answer: (B)

Immunodeficiency increases susceptibility to dermatophyte infections like tinea cruris because the body's defenses against fungi—especially cell-mediated immunity and neutrophil function—are weakened. In HIV or diabetes, impaired immune responses allow dermatophytes to colonize and spread more easily in warm, moist groin skin. This systemic vulnerability makes infection more likely and is a particularly strong, clinically relevant risk factor. While increased skin moisture and warmth also promote fungal growth, they are environmental factors that can affect many people, whereas immune compromise represents a key host factor that raises baseline risk across different situations. Hypothyroidism isn’t a typical risk factor for tinea cruris, and frequent sunscreen use doesn’t contribute to groin fungal infections.