The present report describes a case of cutaneous protothecosis caused by Prototheca wickerhamii in a nonimmunocompromised Brazilian female. Dermatological examination revealed a 15-cm diffusely infiltrated eczema-like plaque recovered with many pustule-like lesions on the right forearm. We emphasize the mycological and pathological aspects of this infection that can lead to misdiagnosis. The patient was successfully treated with itraconazole.