**26. Histological features of pleuropulmonary endometriosis**

There are 21 cases of documented pleural endometriosis involving exclusively the right side of thorax and 17 cases of pulmonary endometriosis. These cases were associated with abdominal endometriosis in one third of the cases and with uterine operations in half of the cases. The development of pulmonary endometriosis suggests an embolic origin of the endometrial implants, while the pleural involvement is explained by the passage of endometrial implants through diaphragmatic lymphatics or defects.
