[Diagnostic pitfalls in bronchopulmonary tumors].

Bronchopulmonary cytopathology is an already old diagnostic method for lung tumours. Its has been the subject of renewed interest following the development of techniques which complete brushing and aspiration by bronchial fibroscopy such as bronchoalveolar lavage, transthoracic pulmonary fine needle biopsy and transbronchial and transtracheal needle biopsy. Diagnostic difficulties depend on both the tumour type and the biopsy technique. Keratinizing squamous cell carcinoma is difficult to distinguish from dyskeratotic cells on aspiration cytology and inflammatory and granulomatous necrosis on transparietal lung biopsy. Non-keratinizing squamous cell carcinoma must not be confused with atypical metaplastic cells on bronchial brushing. Bronchioloalveolar carcinoma must be distinguished from reactivated bronchioloalveolar cells on bronchial aspiration; pulmonary adenocarcinoma must not be confused with atypical bronchiolar cell hyperplasia on transparietal lung biopsy. The naked nuclei of small cell carcinoma on bronchial brushing and transparietal lung biopsy differ from those of malignant small cell lymphoma and carcinoid. Bronchopulmonary cytopathology is able to diagnose the main types of bronchial and pulmonary tumours with a good sensitivity. The overall sensitivity of detection is excellent, ranging between 90 and 92% depending on the method. The false-positive rate is less than 0.5% for experienced cytopathologists.