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case_images: Clinical photos of the patients. (a-d) Diffuse infiltrated erythematous plaques observed on the dorsal side of the left forearm and back of the left hand. These plaques are accompanied by multiple insect-bite-like erosions, ulcers, papules, pustules, atrophic scars, and scabs within the affected area. (e and f) Following a 3-month treatment of oral terbinafine at a dosage of 250 mg/day combined with topical 1% naftifine-0.25% ketoconazole cream, an improvement in skin lesions was observed. Fibrotic scars emerged on the flexor aspect of the left arm as the skin lesions evolved.
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case_images: Within the affected area, numerous insect bite-like papules, ulcers, papillae, pustules, atrophic scars, and scabs were observed (Figure 1a-d). Over 3 months of treatment, the skin lesions continued to improve, resulting in wound healing and leaving behind only fibrotic scars (Figure 1e and f).
case_images: Histological Features of the Patient. (a) Pseudoepitheliomatous hyperplasia and granulomatous inflammation accompanied by localized necrosis and abundant inflammatory infiltration (H&E, magnification x50). (b) Numerous morula-like formations highlighted through Periodic Acid-Schiff staining (magnification x200). (c) Acid-fast stain: negative (magnificationx50). (d) hexamine silver stains: positive (magnification x200).
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case_images: Histopathological analysis depicted granulomatous inflammation with necrosis in the dermis, revealing abundant non-budding spherical structures observed under 100x magnification (Figure 2a). Highlighted in Figure 2b were multiple sporangia containing endospores, displaying a morula appearance. Conversely, acid-fast staining yielded negative results (Figure 2c), while hexamine silver staining showcased positivity (Figure 2d). 
case_images: Colony Growth and Characteristics of Prototheca wickerhamii under Microscopy. (a) Smooth, creamy, white, and yeast-like colonies observed on SDA culture after 48 hours of incubation at 30 C. The characteristic endospore-containing sporangium of Prototheca wickerhamii. (b) Wet preparations stained with lactophenol cotton blue and (c) fluorochrome revealing the distinction from yeast due to the absence of budding.
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case_images: Culturing the biopsy specimen on Sabouraud dextrose agar (SDA) at 30 C resulted in smooth, creamy white, yeast-like colonies after 48 hours (Figure 3a). Further microscopic examination stained with lactophenol cotton blue and fluorochrome revealed characteristic endospores scattered or enclosed in a sporangium (Figure 3b and c).