Histopathology of respiratory system and mediastinum

Biopsies from respiratory system like bronchial and lung parenchymal are among the commonest ones. Besides conventional bronchoscopic biopsies, tiny CT-guided biopsies are also frequent. On the flip side, treating physicians require more and more information not only in terms of a definitive entity but also what therapy they are likely to respond. This puts immense pressure on the pathologists to be highly judicious in performing IHC markers to leave enough tissue for mutational analysis like EGFR, ALK, ROS1 and PD-L1. Among non-neoplastic lesions, ‘interstitial lung diseases’ are among the most demanding and challenging with subtle and overlapping features requiring quick revision of the subject. Pleural biopsies are also at times challenging. Mediastinal pathology is markedly diverse, and almost any kind of pathology may be seen in this region. In this chapter however our focus is on those entities which are indigenous to this region like various types of thymoma.