Diffuse infiltrative lung disease: a new scheme for description.

A scheme was devised for semiquantitative description of the diffuse infiltrative lung diseases using the graphic terminology of the International Labour Office and Union Internationale Contre le Cancer (ILO/UC) classification. Conventions for grading the type (rounded or "pqr" and irregular or "stu"), severity (profusion in 12 steps), localization of opacities, and pleural disease were retained. Modifications included: (a) a third group of opacities, called "xyz," corresponding to reticulonodular patterns; (b) "ground glass" (alveolar) patterns, subdivided into 7 types by character and location; (c) notations for severity of emphysema; and (d) hilar node enlargement. This initial study concerned diagnostic aspects and therefore was limited to 365 cases proved by open biopsy. When this scheme was used without any knowledge of clinical data, the first two radiologic diagnostic choices corresponded with the principal histologic diagnosis in 50% of cases. The biopsy diagnosis was mentioned among the first three choices in 78% of cases. It is concluded that this classification provides an understandable and quantifiable system of communication and a tool for teaching, clinical research, and epidemiologic studies.