Supplementary Material for: Nicolau syndrome following benzathine benzylpenicillin injection in a patient with syphilis and type 2 diabetes: A Case Report

Introduction: Nicolau syndrome (NS) is a rare complication following intramuscular (IM), intra-artricular, or subcutaneous injections, marked by severe localized pain, skin discoloration, and tissue necrosis. Treatments focus on halting causative agents, pain control, and preventing secondary infections. Here we describe a case of NS due to the use of penicillin G benzathine for syphilis. Case Presentation: A 39-year-old male presented with a painful rash on his left buttock three minutes after intramuscular injection of penicillin G benzathine for the treatment of syphilis. The patient, with a history of type 2 diabetes, experienced significant complications including rhabdomyolysis (RM) and liver dysfunction. After the treatments of corticosteroids, anticoagulation, fluid resuscitation and alkalinizing the urine, the patient recovered well. Conclusion: Nicolau syndrome may result from accidental arterial injection (causing vascular occlusion) or hypersensitivity reactions to medications. We reported the clinical course of a case of NS and highlight the need for proper injection technique, early intervention, and multidisciplinary care to manage NS and its complications.