Diagnostic invasive procedures in diffuse infiltrative lung diseases

The diagnosis of infiltrative diffuse lung disease may require invasive procedures after all noninvasive tools have failed. The clinical context in which these diseases develop and the radiological patterns are crucial for defining the timing and the methods to be used. Immunocompromised hosts are usually acutely ill with fever, cough, shortness of breath, and often with progressive hypoxemia. In this context a prompt diagnosis is necessary to decrease mortality. Bronchoalveolar lavage [especially in cases that show ground-glass attenuation or alveolar opacification in high-resolution CT scan (HRCT)] is the most important invasive procedure allowing the identification of infectious agents, neoplastic elements and characteristic cytological and phenotypical profiles (for drug injury) in the majority of cases. Less frequently transbronchial lung biopsy, transbronchial needle aspiration and biopsy or surgical lung biopsy are necessary. In immunocompetent patients the clinical spectrum of diffuse lung disease is quite broad. Furthermore, in the last two decades HRCT, used in conjunction with clinical and other noninvasive investigative modalities, has increased the accuracy of diagnosis for some diseases without the need of surgical biopsy. Also in these patients bronchoalveolar lavage, frequently in combination with transbronchial lung biopsy, is sufficient to achieve a definitive diagnosis in the majority of cases. Surgical lung biopsy is, however, still relevant in cases with idiopathic interstitial pneumonias. In this article invasive diagnostic procedures in patients with diffuse lung infiltrates are discussed from the perspective of their clinical context and their imaging characteristics.