Endoscopic diagnosis of central lung cancer: growth patterns and bronchoscopic features

Central lung cancer is characterized by different patterns of tumor growth in relation to the bronchial wall and lumen, which determine the bronchoscopic appearance, feasibility of obtaining representative tissue, and choice of method for morphological verification. The anatomical and clinical classification proposed by A.I. Savitsky, distinguishing endobronchial, peribronchial nodular, and peribronchial branching forms of central lung cancer, remains clinically useful for interpreting endoscopic findings. The aim of this clinical lecture is to systematize the bronchoscopic features of central lung cancer according to the predominant direction of tumor growth and to demonstrate their significance for diagnostic strategy. Direct and indirect bronchoscopic signs, features of endobronchial and peribronchial involvement, mixed growth patterns, and proximal bronchial involvement during progression of initially peripheral lung cancer are discussed. Particular attention is paid to situations in which extensive tumor involvement is not accompanied by a clearly visible intraluminal component and is manifested mainly by bronchial deformation, narrowing, and wall rigidity. The absence of visible tumor tissue within the bronchial lumen does not exclude central lung cancer and requires assessment of the bronchial wall, lumen, interbronchial spurs, and bronchial orifices. Principles for selecting a method of tissue acquisition according to the location of pathological tissue are considered, including forceps biopsy, endobronchial cryobiopsy, and endobronchial ultrasound-guided techniques. The importance of small biopsy specimens suitable for integrated morphological, immunohistochemical, and molecular genetic assessment is emphasized. The current goal of endoscopic biopsy is to obtain representative tissue sufficient for histological typing, immunohistochemical analysis, and molecular genetic testing. Understanding the predominant tumor growth pattern facilitates accurate interpretation of bronchoscopic findings and rational selection of the method of morphological verification.