The diagnosis of sarcoidosis can be supported by biopsy of clinically involved extrathoracic sites, including skin lesions, conjunctiva, lacrimal glands, superficial lymph nodes, and liver. The sensitivity of fiberoptic bronchoscopy with transbronchial biopsy ranges from 60% to 90%; the yield with this modality increases as radiographic staging increases. Endoscopic ultrasound-guided fine-needle aspiration detects noncaseating granulomas in 82% of patients who have sarcoidosis of stage I or II. However, a negative sample drawn by fine-needle aspiration must be interpreted cautiously because the amount of culture material provided by fine-needle aspiration is small; an examination of lymph node architecture is required to rule out other diseases. In cases in which the results of fiberoptic bronchoscopy are inconclusive, a surgical procedure - either mediastinoscopy or lung biopsy by video-assisted thoracoscopic surgery - may be required to establish the diagnosis.