Tinea cruris typically spares which anatomical area?

Explanation

## Tinea Cruris: Characteristic Sparing Pattern **Key Point:** Tinea cruris (jock itch) characteristically spares the scrotum, despite affecting the surrounding inguinal and perineal areas. This is a classic clinical finding that aids diagnosis. ### Why Scrotum Is Spared 1. **Thin, delicate epidermis** — The scrotal skin lacks the thick stratum corneum required for dermatophyte colonization. 2. **High moisture and maceration** — While these favour fungal growth, the scrotal epithelium does not support sustained dermatophyte infection. 3. **Lack of keratin substrate** — Dermatophytes require keratinized tissue; scrotal skin is relatively non-keratinized. ### Typical Distribution of Tinea Cruris | Area | Involvement | |------|-------------| | Inguinal folds | **Always affected** — primary site | | Inner thighs | **Commonly affected** — bilateral, symmetric | | Perianal region | **Often involved** — extends posteriorly | | Scrotum | **Spared** — does not show lesions | | Penile shaft | Usually spared (unless candidiasis) | **High-Yield:** The **scrotum-sparing pattern** is a distinguishing feature of tinea cruris vs. candidiasis (which *does* involve the scrotum and glans). **Clinical Pearl:** If a patient with inguinal dermatitis has scrotal involvement, consider candidiasis, erythrasma, or inflammatory dermatitis rather than tinea cruris.