Human Protothecosis: Case Report of a Rare Algal Infection

Protothecosis: is a rare disease caused by opportunistic algae infection of the genus Prototheca. An 84-year-old female patient has presented with an erythematous, infiltrated, papulopustular plaque with areas of central atrophy on the left forearm for the past 10 months. Histopathology revealed structures similar to morulae, corresponding to algae, and culture was positive for Prototheca spp. Itraconazole 200 mg/day was prescribed, resulting in improvement of cutaneous lesions. Protothecosis has a high potential for underreporting and misdiagnosis due to its rarity and linical similarities with other dermatoses. The patient in this study presented a lesion in a typical area due to the ease of trauma and entry point, with a good therapeutic response to oral antifungal monotherapy.