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Vascular-penetration defect detected in parietal pleura of primary spontaneous pneumothorax.

Primary spontaneous pneumothorax (PSP) is one of the most frequent diseases that thoracic surgeons handle, but the aetiology is not really known. We prospectively examined intraoperative images and collected the data of PSP patients who received bullectomy and mechanical pleurodesis with the thoracoscope at the Department of Thoracic Surgery at our hospital. Vascular-penetration defects (VPDs) were 2-6 mm vessel-converged holes that we found on the apex of the parietal pleura of PSP patients exclusively. The VPDs were solely located in the apex of the parietal pleura on the chest wall above the first rib. As many as up to four in number could be present. The VPDs were sometimes complementary to blebs and were not found in any of the other thoracoscopic surgeries for diseases other than PSP. We postulate that the presence of VPDs may be a contributing factor to the formation of a subgroup of emphysematous-like changes and the recurrence of PSP.