Descending necrotizing mediastinitis and the proposal of a new classification

OBJECTIVE: We aimed to clarify the clinical features and surgical outcomes of descending necrotizing mediastinitis (DNM) to provide a guide for its surgical treatment, focusing on the type of extension and the deployed procedures. METHODS: As a joint study of the Japan Broncho-esophagological Society and the Japanese Association for Chest Surgery (JBES1703/JACS1806 study), the clinical data of consecutive patients with DNM who underwent surgical drainage between 2012 and 2016 were collected from 131 participating institutions. The infection limited to the area superior to the carina level was defined as type I; while spreading to the lower mediastinum (LM) as type II. The LM infection limited to the anterior LM, that spread to both the anterior and posterior LM and that limited the posterior LM (type IIC) were further categorized as type IIA, IIB, and IIC, respectively. RESULTS: A total of 225 patients were ultimately eligible. One hundred patients (44.4%) were categorized as type I, whereas 125 patients were type II (56.6%); The number of type IIA, IIB, and IIC cases was 20 (16%), 62 (49.6%) and 43 (34.4%), respectively. Patients with type I and IIC infections more commonly underwent cervical drainage than patients with type IIA and IIB infections (34.3% and 13.4%, respectively). A total of 8 patients died within 30 days (3.6%, type I/II: 1/7). The 5-year overall survival rate was 68.6%. Type II infection was associated with the 90-day mortality (odds ratio, 5.18; P = .045). CONCLUSIONS: This study demonstrated a previously unclassified group of lower mediastinal extent that is localized within the posterior mediastinum (type IIC). We proposed a new DNM classification including type IIC mediastinitis.