Cytopathology of pleural endometriosis

Cytomorphologic features in pleural effusions obtained from two cases of endometriosis of the pleura are described. These young patients presented with recurrent right pneumothorax and hemorrhagic pleural effusions. In the pleural fluid specimens, recognition of endometrial epithelial cells, which generally occur in tissue fragments or singly, and of hemosider in-laden histiocytic cells, which probably represent endometrial stromal elements, is considered essential to establishing such a diagnosis on a morphologic basis alone. A brief review of the literature is presented.