Abstract
A case of agenesis of the right middle lobe, which is a very rare condition, is reported. A 48-year old woman was admitted for examination of an abnormal chest shadow. Chest X-ray showed a mass shadow in the left lower lung field, but in the right lung no definite abnormal shadow was pointed out. The mass was diagnosed as adenocarcinoma, and left lower lobectomy was performed. On bronchoscopy the orifice of the right middle lobe bronchus was not present. On bronchography absence of the right middle lobe bronchus was confirmed, and there was downward displacement of the right B^3b and upward displacement of the right B^<8+9>. Pulmonary angiography showed the absence of the middle lobe artery. As chest CT revealed that emphysematous change and mucocele were not present in the right lung, bronchial atresia was ruled out in this case.
