An extensive skin defect and necrotizing fasciitis derived from a neglected epidermal cyst on the upper back: A case report

RATIONALE: Epidermal cysts are one of the most prevalent skin lesions encountered in clinical practice. Although generally harmless, complications may arise when epidermal cysts are neglected, leading to potentially severe consequences, such as necrotizing fasciitis. Here, we report an unusual case of an extensive soft-tissue defect and necrotizing fasciitis resulting from an untreated epidermal cyst on the upper back. PATIENT CONCERNS: A 37-year-old male patient presented with a 12 × 10 cm epidermal cyst on his back with severe inflammation. The patient was also diagnosed with diabetes mellitus, which raised the need for comprehensive medical and surgical evaluations for treatment. DIAGNOSES: Magnetic resonance imaging revealed a broad soft-tissue defect with necrotizing fasciitis involving the back muscles. INTERVENTIONS: Extensive debridement was performed, and various approaches were used to address the challenging wound size. After debridement, a soft-tissue defect measuring 35 × 30 cm was identified, and negative-pressure wound therapy followed by split-thickness skin grafting was used to cover the wound. OUTCOMES: At the 6-week post-surgery follow-up at the outpatient clinic, the patient exhibited a completely healed wound, and the patient's uncontrolled diabetes mellitus was managed. LESSONS: This case underscores the importance of not overlooking epidermal cysts and considering surgical intervention when they result in substantial skin and soft-tissue defects.