dermatologic disorders
Erythrasma
Diagnosis of Erythrasma
Clinical evaluation Erythrasma fluoresces a characteristic coral-red color under a Wood light due to production of porphyrin by the causative bacterium. Absence of hyphae in skin scrapings also distinguishes erythrasma from tinea. Differential diagnosis of perianal erythrasma includes perianal streptococcal cellulitis. Perianal streptococcal cellulitis causes pain and bright red erythema solely on perianal skin and lacks fluorescence on Wood light examination. Cultures for group A streptococcus done on skin swabs from affected children are positive. 