Parietal pleural small holes found in patients with primary spontaneous pneumothorax associated with relatively mild chest wall flatness: a retrospective study

BACKGROUND: During surgery for spontaneous pneumothorax, parietal pleural small holes (PPSHs) are occasionally found around the apex of the intrapleural space; however, this has not been well recognized. Additionally, chest wall flatness is usually observed in patients with primary spontaneous pneumothorax (PSP) and PPSHs. This study aimed to investigate the prevalence of PPSH and evaluate the characteristics of patients with PPSH. We also investigated the degree of chest wall flatness in patients with PPSHs. METHODS: We retrospectively reviewed all patients who underwent thoracoscopic surgery for pneumothorax at our department between April 2014 and May 2021. A propensity-matched analysis was used to compare the characteristics of patients with and without PPSH. RESULTS: A total of 490 patients were enrolled in this study. PPSH was found in 45 of 297 (15.2%) patients with PSP and one of 193 (0.5%) patients with secondary pneumothorax. PSP was independently associated with the presence of PPSH after adjusting for age and sex [primary/secondary, odds ratio (OR) =34.3, 95% confidence interval (CI): 4.7–250.9; P<0.001]. Among patients with PSP, the flatness of the chest wall in patients with PPSH was not as severe as that in patients without PPSH {thoracic anteroposterior diameter (APDT) to transverse diameter (TDT) ratio; with PPSH: median =0.517 [interquartile range (IQR) =0.480–0.554] vs. without PPSH: median =0.487 (IQR =0.463–0.529; P=0.031)} after propensity score matching. CONCLUSIONS: PPSH is found in a non-negligible proportion of patients with PSP, and patients with PPSHs show a relatively mild flat chest among patients with PSP. Clinicians should be aware of PPSH, and further understanding of this condition may contribute to a better understanding of PSP.