Castleman's disease (CD) is rare and difficult to diagnose preoperatively. We report two similar cases of hyaline vascular type CD diagnosed preoperatively using different modalities. In the first case, a biopsy specimen taken during diagnostic thoracoscopy revealed lymphatic structure suggestive of CD. In the second case, endobronchial ultrasound-guided transbronchial needle aspiration enabled sampling of histological cores for histological diagnosis. In both cases, the final diagnosis was established by surgical resection.