Fig 1.
Visual aspect of visceral and parietal pleural endometriosis.
Visceral pleural endometriosis showed (A) brown nodule, and (B) cystic lesion. Brown nodule was like a hematoma, to say it in another way blueberry spot. Parietal pleural endometriosis showed (C) brown nodule, and (D) dent of the pleura called depressed lesion.
Table 1.
Patient characteristics (n = 160).
Fig 2.
Distribution of endometriotic lesions.
(A) Visceral pleural lesions, and (B) Parietal pleural lesions. Eighty-six visceral pleural lesions (82.7%) out of 104 were observed in S4, S6, and S2. Eighty-seven parietal pleural lesions (86.1%) out of 101 were observed in 4th-9th dorsal intercostal space.
Fig 3.
Localization of endometriotic lesions in the visceral pleura.
(A) Endometriotic tissue adhered to the surface of the visceral pleura. Note that marked hemosiderin deposition was observed in the entire pleural wall. (Hematoxylin-Eosin stain, inset: the external and internal elastic layer were indicated by black arrow and arrowhead, respectively (Elastica von Gieson stain)). (B) Endometriotic lesions surrounded by granulation and/or fibrous tissue accompanied with inflammatory cells invaded into the lung tissue through the visceral pleura. (Hematoxylin-Eosin stain, inset: white arrow and arrowhead indicated the break of the external and internal elastic layer caused by the invasion of endometriotic tissue, respectively (Elastica von Gieson stain)). (C) Endometriotic stromal cells in the endometriotic lesion were immune-positive for CD10 (gray arrows) in the same tissue of Fig 3B. Note that the anti-CD10 antibody was cross-reactive to alveolar stromal cells (black arrowhead) and alveolar macrophages (white arrowhead).
Table 2.
Invasion depth of 104 visceral pleural endometriotic lesions, n (%).
Fig 4.
Kaplan-Meier curve of postoperative recurrence rate.
Fig 5.
Flow chart of treatments for 30 patients with postoperative recurrences.
Table 3.
Detailed characteristics of the 6 patients who received reoperations.
Fig 6.
Schematic illustration of breaking of the visceral pleural structure in endometriosis.
Endometriotic tissue migrating in the thoracic space may be located on the surface of the visceral pleura (A). Subsequently, proliferation and breakdown of the endometriotic tissue may occur during menstruation cycles on the surface of pleura as the same fashion of uterus. It may lead to bleeding, tissue repair, and inflammation of the endometriotic lesion involving the surrounding pleural tissue, suggesting stepwise breaking of the pleural structure (mesothelial, sub-mesothelial, external elastic, subpleural, and internal elastic layer) (B-D).