Fatal Cutaneous Mucormycosis Initially Misdiagnosed as Necrotizing Fasciitis in an Uncontrolled Diabetic Patient: A Case Report Highlighting Diagnostic Delay.

BACKGROUND: Mucormycosis is a rare yet highly aggressive invasive fungal infection associated with significant mortality, particularly among patients with uncontrolled diabetes mellitus. Early diagnosis remains challenging because its clinical presentation may closely mimic bacterial necrotizing soft tissue infections, particularly in critically ill patients, while conventional diagnostic tests such as potassium hydroxide (KOH) smear have limited sensitivity. CASE PRESENTATION: We report a 64-year-old male with undiagnosed diabetes who presented with progressive decline in consciousness and extensive necrotic lesions over the occipital and periorbital regions. On admission, he was in septic shock with complications including acute kidney injury, arrhythmia, and multi-organ dysfunction. The initial working diagnosis was bacterial necrotizing fasciitis, supported by an initial false-negative KOH smear, resulting in empiric broad-spectrum antibiotic therapy and surgical debridement. Subsequently, wound cultures grew carbapenem-resistant Acinetobacter baumannii (CRAB), further reinforcing the presumed bacterial etiology and complicating clinical management. Necrotic tissue culture ultimately confirmed mucormycosis, and amphotericin B was initiated only after fungal culture confirmation. Despite combined medical and surgical interventions, the patient's condition deteriorated, and he died on the twelfth day of hospitalization. This case illustrates how diagnostic anchoring, limited sensitivity of initial mycological investigations, and bacterial co-infection contributed to delayed recognition of invasive mucormycosis and postponed appropriate antifungal therapy. CONCLUSION: Mucormycosis in uncontrolled diabetes carries a poor prognosis when diagnosis and treatment are delayed. Clinicians should maintain a high index of suspicion for mucormycosis in diabetic patients presenting with rapidly progressive necrotic soft tissue infections despite negative initial fungal microscopy or the isolation of bacterial pathogens. Early deep tissue biopsy, repeat mycological investigations, and timely empirical antifungal therapy should be considered when clinical suspicion remains high.