Thoracic pseudo-lesions induced by inadequate methodology, visual illusions or anatomical variations

False-positive or over-calling of findings at chest radiography may have im portant consequences by generating numerous and unnecessary examinations. T he advances made in thoracic imaging have currently decreased the number of technical errors. However, we are frequently confronted with visual illusi ons or with failure to recognize anatomical variants, either congenital, ag e-related or physiological in nature. Other difficulties are due to functio nal variations. Over-calling depends on the clinical context, which may ina dequately suggest an interstitial lung process, abnormalities of the vascul arization or of the hila. In this article, several examples of false positi ves will be illustrated. An explanation for these appearances, based on the underlying etiology, will be provided.