Study objectives: We investigated the macroscopic features of bilateral pneumothorax (BLP) and compared them with those of unilateral pneumothorax (ULP).
Methods: Surgical cases of spontaneous pneumothorax (236 cases) were divided into two groups based on unilateral occurrence (206 cases) or bilateral occurrence (30 cases). The patients were divided into three groups by the macroscopic findings of lung disease. The first group consisted of those patients with solitary and small bullae (type I pneumothorax), the second group consisted of those with multiple and large bullae (type II pneumothorax), and the third group consisted of those with an aggregation of diffuse and tiny bullae (type III pneumothorax).
Results: In metachronous BLP cases, 18 patients (66.7%) revealed type III pneumothorax in the first occurrence site, and 13 of 18 patients (72.2%) revealed type III pneumothorax in the contralateral site. Type III pneumothoraces were more frequently found in patients with BLP (18 of 27 patients; 66.7%) compared with ULP (73 of 206 patients; 35.4%; p = 0.0086 [χ2 test]). During a follow-up ranging from 12 to 129 months (median, 69 months), 7 patients (23.3%) in the BLP group developed recurrences. This rate was higher than that of the ULP group (5.3%; p = 0.0009 [χ2 test]). Contralateral CT scan findings of their first occurrence were retrospectively reviewed. In 3 patients (15.8%) in the BLP group and 17 patients (12.3%) in the ULP group, apical lung bullae and blebs (ruptured or intact) could be detected on the contralateral lung (p = 0.703 [χ2 test]).
Conclusions: The patients with an aggregation of diffuse and tiny bullae in their thoracoscopic findings had a high risk of contralateral recurrence. Macroscopic lung appearance in the contralateral site in such patients tended to reveal the same type as that in the primary site. CT scanning was not useful for predicting the risk of contralateral occurrence.