Correlation of histopathologic findings with clinical outcome in necrotizing fasciitis

Background. Necrotizing fasciitis is an uncommon disease with high morbidity and mortality rates. Little is known about the role of histopathologic examination in disease prognosis. Methods. A retrospective study was conducted to determine what correlations, if any, exist between the histopathologic features of resected tissue in patients with necrotizing fasciitis and clinical outcome. Results. Eighty-two cases of necrotizing fasciitis that occurred between January 1990 and December 2002 were identified. Histopathologic findings were available for review in 63 cases. A novel histopathologic classification scheme, based on hematoxylin-eosin and Gram stain results, was developed. The classification scheme included 3 stages: stage I, characterized by an intense neutrophilic response and an absence of bacteria in infected tissue; stage II, characterized by the presence of a moderate-to-severe neutrophilic response and positive Gram stain results or by minimal to absent neutrophilic response with a negative Gram stain result; and stage III, characterized by the presence of few or no polymorphonuclear leukocytes and a Gram stain result positive for bacteria during histopathologic examination. Patients with stage I findings had a significantly lower risk of death than patients with stage III findings (7.1% vs. 47%; odds ratio [OR], 0.1; 95% confidence interval [CI], 0.01 - 0.8; P = .03). Patients with stage II findings had a significantly lower mortality rate than patients with stage III findings ( 14.2% vs. 47%; OR, 0.2; 95% CI, 0.04 - 0.9; P = .04). Due to the small number of deaths (n = 11) in patients for whom histopathologic examination of resected tissue was performed, multivariate analysis was not done. Conclusions. Results of this study suggest that histopathologic findings may correlate with clinical outcome in cases of necrotizing fasciitis. Because the histopathologic scheme is based on results of commonly available stains, it could be easily adopted for use in other institutions that could further evaluate its usefulness as a prognostic tool.