Despite the considerable progress in the classification of the idiopathic interstitial pneumonias (IIPs), the lack of an international standard has resulted in variable and confusing diagnostic criteria and terminology. The advent of high-resolution computerized tomography, the narrowed pathologic definition of usual interstitial pneumonia (UIP) and recognition of the prognostic importance of separating UIP from other IIP patterns have profoundly changed the approach to the IIPs. This is an international Consensus Statement defining the clinical manifestations, pathology, and radiologic features of patients with IIP. The major objectives of this statement are to standardize the classification of the idiopathic interstitial pneumonias (IIPs) and to establish a uniform set of definitions and criteria for the diagnosis of IIPs. The targeted specialties are pulmonologists, radiologists, and pathologists. A multidisciplinary core panel was responsible for review of background articles and writing of the document. In addition, this group reviewed the clinical, radiologic, and pathologic aspects of a wide spectrum of cases of diffuse parenchymal interstitial lung diseases to establish a uniform and consistent approach to these diseases and to clarify the terminology, definitions, and descriptions used in routine clinical practice. The final statement was drafted after a series of meetings of the entire committee. The level of evidence for the recommendations made in this statement is largely that of expert opinion developed by consensus. This classification of IIPs includes seven clinico-radiologic-pathologic entities: idiopathic pulmonary fibrosis (IPF), nonspecific interstitial pneumonia, cryptogenic organizing pneumonia, acute interstitial pneumonia, respiratory bronchiolitis-associated interstitial lung disease, desquamative interstitial pneumonia, and lymphoid interstitial pneumonia. The need for dynamic interaction between pathologists, radiologists, and pulmonologists to accurately diagnose these disorders is emphasized. The level of evidence for the recommendations made in this Statement is largely that of expert opinion developed by consensus. This Statement is an integrated clinical, radiologic, and pathologic approach to the classification of the IIPs. Use of this international multidisciplinary classification will provide a standardized nomenclature and diagnostic criteria for IIP. This Statement provides a framework for the future study of these entities. Key Messages * Unclassifiable interstitial pneumonia : Some cases are unclassifiable for a variety of reasons (see text). † This group represents a heterogeneous group with poorly characterized clinical and radiologic features that needs further study. ‡ COP is the preferred term, but it is synonymous with idiopathic bronchiolitis obliterans organizing pneumonia.

Neuroendocrine tumors of the lung embrace a spectrum from low-grade typical carcinoid (TC), intermediate-grade atypical carcinoid (AC), and high-grade categories of large cell neuroendocrine carcinoma (LCNEC) and small cell carcinoma (SCLC). We studied 200 neuroendocrine lung tumors to critically evaluate the Arrigoni histologic criteria for AC using statistical analysis to delimit more rigorously an intermediate survival for AC between TC and the high-grade tumors of LCNEC and SCLC. Histologic features that might predict prognosis were used for Kaplan-Meier and Cox proportional hazards survival analysis, and an optimal mitotic range for AC was calculated. The optimal mitotic range for AC was 2 to 10 mitoses per 2 mm2 of viable tumor (10 high-power fields). Based on this finding, we collapsed mitoses into three categories (< 2; 2-10; > or = 11) and performed Cox multivariate analysis for all 200 neuroendocrine tumors. Mitotic counts were the only independent predictor of prognosis. Based on this analysis, we propose that AC be defined as a tumor with neuroendocrine morphology, mitotic counts between 2-10 per 2 mm2 of viable tumor (10 high-power fields), or coagulative necrosis. Using these criteria, the 200 neuroendocrine tumors were classified as 51 TC, 62 AC, 37 LCNEC, and 50 SCLC. The 5- and 10-year survival was 87% and 87% for TC, 56% and 35% for AC, 27% and 9% for LCNEC, and 9% and 5% for SCLC, respectively. After stratification for stage, survival for AC was significantly worse than for TC (p < 0.001); for LCNEC and SCLC it was significantly worse than for AC; but the survival for LCNEC was no different than that for SCLC.