Diffuse interstitial lung diseases constitute a heterogenous group of clinical problem which share signs and symptom of clinical presentation, may present different stages of more or less diffuse radiologic involvement, and carry usually poor prognosis.

Pathological inflammatory process is a the key pathophysiological phenomenon, and usually involves the interstitium, that is the area between alveolar epithelium and capillary endothelium and interstitial matrix which supports vessels and bronchi.

Diagnosis is bases on the clinical presentation, accessory investigations, among them serology, immunology, but mostly on radiology (especially on HRCT – high resolution computed tomography – which rarely is pathognomonic). The final diagnosis usually requires cytologic and histologic confirmation based on invasive investigations: endoscopy of the bronchi, transthoracic biopsy, video-assisted thoracoscopy or open lung biopsy.

This review covers the clinical utility of invasive pulmonary and thoraco-surgical procedures in the diagnostic work-up of diffuse lung disease.