Combined atelectasis of right upper and middle lobes: a clinical study of 15 cases.

Because of the independent and remote origin of the right upper and middle lobe bronchi, combined collapse of right upper and middle lobes is thought to be uncommon. We report 15 cases of combined right upper and middle lobe collapse found by plain chest radiograph in the past 8 years. Malignancies were confirmed in 13 cases. The other 2 cases with benign etiology included one case of endobronchial TB and one of pneumonia. These cases of combined bilobar collapse were possibly due to (1) the intraluminary infiltration of the primary tumor of the upper lobe to the middle lobe bronchus, (2) separated area of collapse produced by the primary tumor and its metastatic lymphadenopathy, (3) upper lobe tumor with external compression to intermediate bronchus that obstructed both the upper and middle bronchi, (4) multi-centric neoplasm, (5) tumor obstruction and sputum impaction at different bronchi, or (6) benign lesions operated at two different locations. The more frequent occurrence of bronchogenic carcinoma than that of benign lesions in our study revealed the invalidity of the "double lesion sign". Bronchoscopy or CT scan should be used to search for the etiology. If malignancy is confirmed in such condition, the prognosis is usually poor due to its advanced invasion.