<原著>局所性肺過膨張を伴なう気管支嚢腫 (bronchocele)

Abstract

The bronchocele (bronchial mucocele) is developed by the gradual accumulation of mucus in the distal portion of obstructed bronchial tree. The cause of the occlusion may be congenital structural defect of the bronchus, cicatrical shrinkage of the bronchial lumen or neoplasm and so on. While the lober bronchial atresia produces invariably atelectasis, segmental or subsegmental bronchial atresia may not produce any change in volume of the involved lung segment or subsegment. Most of the mucocele due to bronchial atresia have shown a striking degree of focal hyperinflation on the involved area because of the presence of collateral ventilation and check valve mechanism of the involved airways. This complex of bronchial atresia and focal emphysema was reviewed by Talner and others. In these reports they did not clear the origin of the bronchocele and the mechanism of development of hyperinflation. In the present paper 4 patients with this syndrom are reported and some explanations on the development of bronchocele and hyperinflation mechanism are discussed based on the clinical and histological observations. The cases were clinically examined on serial retrospective evaluation of roentgenograms, bronchograms, pulmonary arteriograms and so on. All cases were performed resection of the involved area and the specimens of the resected lung were examined by inflating through the dissected bronchi and were sectioned along bronchi for further histological evaluations. The serial retrospective chest roentgenograms of the 3 out of 4 patients (a 9 y. o. boy and two 14 and 21 y. o. girls) showed tumor-like shadows near hila and increased hyperlucent region on the distal portion of the tumor since their childhood. In another 26 y. o. man, a mass of shadow appeared on his chest roentgenogram at the age of 24. At thoracotomy, all of 4 cases showed segemental or subsegmental bronchial atresia with regional bronchocele and the focal hyperinflation with air trapping as compared with normally ventilated adjacent regions. The findings were located in the left S_<1+2> of the 3 cases and right upper lobe of 1 case in which a congenital bronchial cyst was accompanied in right lower lobe near mediastinum. It was confirmed that there was coexistence of regional immature bronchial cartilage formation and focal emphysema which suggested the relationship between collaps of the small bronchus and the regional emphysema. Another observation showed that the check valve mechanism induced from partial obstruction of segmental bronchus compressed by the bronchocele together with the surrounding segments developed to the hyperinflation of distal portion of the lung. These observations might prepare one of the clues to solve the mechanism of this syndrom.