Begins with an erythematous patch on the proximal medial thigh
Inward spread with partial central clearing
Sharply demarcated border, erythematous, elevated
May spread to perineum, perianally, onto buttocks, or into gluteal cleft
Typically spares the scrotum
Tinea cruris
Erythrasma 
Tinea corporis
Seborrheic dermatitis
Tinea capitis
Candidal intertrigo 
Tinea versicolor
Inverse psoriasis