[Thoracic imaging in AIDS].

Chest complications were the first known in AIDS; even, Pneumocystis carinii pneumonia was the initial warning light. At the present time lung complications remain the major cause of death in such patients. A better knowledge of these pathologies often allows to pass an acute episode and perhaps to prevent infectious pathologies, so, leading to the observation of extra-thoracic pathologies. Preventive treatments and increasing survival time allow the appearance of some atypical aspects of Pneumocystis carinii pneumonia such as apical, necrotic or pseudotuberculous forms. On the other hand, lung tuberculosis is observed with a particular frequency in these patients. It has very rarely a nodular or excavated aspect and looks frequently like a primary tuberculosis. If such infectious chest complications have to be recognized very quickly, we have to know the possibility of non infectious disease, and firstly of Kaposi's sarcoma. Radiological aspect, especially from chest-X-ray, is one of the first diagnostic guide. It gives the orientation for other examinations opposing, disseminated or diffused pneumopathy to focal or localized one. In the first group, we have to distinguish alveolo-interstitial patterns from nodular patterns. Necrotic or suppurative aspects and the association with pleural, mediastinal or hilar lesions are important signs, sometimes better shown on CT scan. Moreover, chest-CT scan is able to guide new endoscopic samples or to guide transthoracic biopsies, allowing sometimes to avoid an open lung biopsy.