坏死性筋膜炎（NF）是一种罕见但可能致命的疾病。它被定义为细菌快速扩散的皮下软组织感染。NF延伸到腹膜后可能会使这种致命性的疾病进一步复杂化。我们报告了1例37岁的患者，因肛周疼痛、红肿、脓性渗出和发热症状就医。经过详细检查诊断为肛周NF，并已延伸至腹膜后区域，导致腹膜后局部感染。患者入院后接受了抗生素治疗，经治疗后恢复良好，感染得到了控制，最后顺利出院。

Necrotizing fasciitis(NF) is a rare but potentially fatal disease. It is defined as a subcutaneous soft tissue infection in which bacteria spread rapidly. NF extending retroperitoneally may further complicate this deadly disease. We report a 37-year-old patient who sought medical attention for perianal pain, redness, purulent exudation, and fever. Upon detailed examination, the diagnosis was perianal NF, which had extended into the retroperitoneal area, resulting in a local retroperitoneal infection. The patient received antibiotics after admission, the patient recovered well after treatment, the infection was controlled, and finally discharged successfully.