Human Cutaneous Protothecosis: Report of a Case and Literature Review
A 68-year-old man presented with an ill-defined erythematous lesion with crust at the dorsal aspect of his left wrist (). The skin lesion developed approximately a month ago without any traumatic history, and the patient complained of poor oral intake and diarrhea for a week. He had been suffering from osteoarthritis and had taken medications for twenty years. He was surgically treated for small bowel perforation, adhesion, and panperitonitis 3 years ago. His occupation was gathering trash for recycling.\nA punch biopsy was performed to reveal the histologic features of granulomatous inflammation with confluent necrosis at the upper dermis containing many Prototheca organisms (, ). On periodic acid-Schiff after diastase digestion special staining, non-budding spherical organisms with multiple sporangia containing endospores were observed with a morula- or cartwheel-like appearance, which is the characteristic feature of the Prototheca species (). The organisms were approximately 20 µm in diameter and had a thick cell wall. Upon crystal violet staining, the organisms exhibited multiple small bluish dots ().\nFor specification of the species, small subunit ribosomal DNA (SSU rDNA) was amplified by polymerase chain reaction using the universal primers NS3 (5'-GCAAGTCTGGCCAGCAGCC-3') and NS8 (5'-TCCGCAGGTTCACCTACGGA-3'). The sequences were submitted to a BLASTn search by using the National Center for Biotechnology database (NCBI; ). The sequences of the SSU rDNA regions of the isolate were 99% identical with Prototheca zopfii.\nThe patient was given antifungal agent itraconazole, and the symptoms were relieved.