Primary Subcutaneous Candidiasis Presenting as a Chronic Eschar-Covered Ulcer: A Diagnostic Challenge in an Immunocompromised Host: A Case Report and Literature Review

Primary subcutaneous candidiasis is a rare, severe opportunistic infection. While Candida albicans is typically a commensal, it can become invasive in immuno-compromised hosts, often mimicking other necrotic skin conditions. We describe an 83-year-old male with High-Risk Myelodysplastic Syndrome (MDS) and Acute Myeloid Leukemia (AML) who developed a non-healing eschar-covered ulcer on his left shin following a minor gardening injury. Despite multiple courses of broad-spectrum antibiotics, the lesion persisted. Initial superficial cultures were dismissed as colonization. However, multiple deep tissue biopsies and High-Throughput ITS2 Sequencing confirmed invasive C. albicans. The patient was treated with intravenous Caspofungin for three weeks, leading to significant wound healing. This case highlights the diagnostic challenge of "atypical" fungal ulcers. It underscores the importance of deep tissue biopsies and molecular sequencing in immunocompromised patients to differentiate invasive pathogens from surface colonization and prevent systemic dissemination.