Cutaneous manifestations of Prototheca infections.

The genus Prototheca comprises several species, the most prevalent of which is Prototheca wickerhamii. These achlorophyllic algae are found in the slime flux of trees and in freshwater environs. Cutaneous infection with these microbes was first reported 30 years ago. Subsequent case reports have described other manifestations including systemic disease. Asymptomatic and stationary cutaneous plaques may be seen in otherwise healthy patients. Susceptibility to infection is ill defined but may involve an inability of neutrophils to effectively eradicate phagocytosed organisms. Characteristic morula are seen histologically. Antifungal medications are the most effective therapy.