Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
Department of Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
Mod Pathol. 2018 Apr;31(4):546-552. doi: 10.1038/modpathol.2017.173. Epub 2017 Dec 15.
Necrotizing soft tissue infections are rare but are associated with high rates of morbidity and mortality. The use of bedside or intraoperative frozen sections has been reported to be associated with faster diagnosis and better outcomes; however, to date no large studies have been published to determine the sensitivity and specificity of frozen sections in this setting. Twenty years of cases suspicious for necrotizing soft tissue infection at a large academic referral center were reviewed, blinded to the final clinical diagnosis (gold standard). Cases were assessed for the number of neutrophils, extent of necrosis, presence of thrombi, bacteria, karyorrhexis, and fibrin, and concordance with permanent sections. A total of 166 cases suspicious for necrotizing soft tissue infection had frozen section slides available for review. Sixty-three cases were clinically determined to be positive and 103 negative. Neutrophils, necrosis, thrombi, bacteria, karyorrhexis, and fibrin were present in both positive and negative cases; however, no histological feature or combination of features was found to be both sensitive and specific for necrotizing soft tissue infection. The combined presence of necrosis and frequent neutrophils was 73% sensitive and 68% specific, with a 58% positive predictive value and 80% negative predictive value. The additional observation of bacteria decreased sensitivity to 32%, whereas raising specificity to 91%, with 69% positive predictive value and 68% negative predictive value. Thirty-two cases (19%) contained findings identified on permanent sections (eg, bacteria) not observed on frozen section slides, highlighting the risk of false negatives owing to technical limitations or sampling errors. Frozen sections in necrotizing soft tissue infections and negative cases may show similar histological findings. Combined with the risk of false negatives, these results suggest that frozen sections are likely to be of limited clinical utility due to lack of sensitivity and specificity, and risk for delayed diagnosis and treatment.
坏死性软组织感染虽不常见，但发病率和死亡率很高。据报道，床边或术中冷冻切片的使用与更快的诊断和更好的结果有关；然而，迄今为止，尚无大型研究发表来确定在此情况下冷冻切片的敏感性和特异性。对一家大型学术转诊中心 20 年来疑似坏死性软组织感染的病例进行了回顾性研究，这些病例在最终临床诊断（金标准）方面是盲态的。评估了中性粒细胞数量、坏死程度、血栓、细菌、核碎裂和纤维蛋白的存在情况，以及与永久切片的一致性。共有 166 例疑似坏死性软组织感染的病例有冷冻切片可供审查。63 例临床诊断为阳性，103 例为阴性。阳性和阴性病例均存在中性粒细胞、坏死、血栓、细菌、核碎裂和纤维蛋白；然而，没有发现任何组织学特征或特征组合对坏死性软组织感染既敏感又特异。坏死和频繁中性粒细胞的联合存在具有 73%的敏感性和 68%的特异性，阳性预测值为 58%，阴性预测值为 80%。细菌的额外观察使敏感性降至 32%，特异性提高至 91%，阳性预测值为 69%，阴性预测值为 68%。32 例（19%）包含在永久切片上发现的（例如细菌）而在冷冻切片上未观察到的发现，突出了由于技术限制或采样错误导致假阴性的风险。坏死性软组织感染和阴性病例的冷冻切片可能显示出相似的组织学发现。由于敏感性和特异性低，以及延迟诊断和治疗的风险，再加上假阴性的风险，这些结果表明，冷冻切片的临床应用可能有限。
