Human Cutaneous Protothecosis: A Case Report and Review of Cases from Mainland China, Hong Kong, and Taiwan

We present a case of cutaneous protothecosis caused by Prototheca wickerhamii infection. The patient was a 72-year-old man with hypoalbuminemia. He responded well to fluconazole treatment. We reviewed this case along with 17 other cases of cutaneous protothecosis reported from mainland China, Hong Kong, and Taiwan. Of the 18 cases, 7 each occurred in mainland China and Taiwan, and 4 occurred in Hong Kong. Thirteen cases were caused by P. wickerhamii (72.2%), and three were caused by P. zopfii (16.7%); in two cases, the species was not identified (11.1%). In all, 9 (50%) patients were immunocompromised, and 10 (55.5%) patients denied having a history of trauma. All patients presented with polymorphic skin lesions, and erythematous papules, plaques, or nodules was the most common presentation (15/18, 83.3%). Genotyping was performed in five cases, mostly by means of small subunit ribosomal DNA amplification (four cases). Susceptibility tests (6 patients) showed that P. wickerhamii was sensitive to amphotericin B and voriconazole but resistant to fluconazole or itraconazole. Treatment succeeded in 15 (83.3%) patients and failed in 3 (16.7%). Our data indicate that the number of cutaneous protothecosis cases is underestimated in China, and the skin lesions have some diagnostic value.