Endometriosis-Associated Pleural Effusion: A Diagnostic Challenge

Abstract While rare, a bloody effusion should raise clinical suspicion of pleural endometriosis in women, especially those who are young or have infertility. Diagnosis may have implications in management as case reports showed differences in recurrence rates based on hormonal or surgical approaches. We present a case of a hemorrhagic pleural effusion in a patient with an enlarged uterus. Our patient is a 37 year old woman with a history of endometriosis and infertility who initially presented with a few months of dyspnea and abdominal pain to an ED, found to have new large pleural effusion and large uterus on CT. Thoracentesis of the right pleural effusion drained 1500 cc of a strongly exudative effusion with LDH of 819 and protein of 5.4. Cytology was negative and she had improved symptoms post thoracentesis. She was then referred to pulmonary clinic when her dyspnea returned and found to have reaccumulation of her pleural effusion within 2 months of drainage. She underwent a second thoracentesis in which 1700 cc of chocolate brown colored fluid was removed, again found to be exudative with negative cytology. Uterine biopsies were also negative for cancer and imaging did not show any other concerns for malignancy. She was referred to thoracic surgery when her symptoms recurred and underwent pleural biopsy and pleurodesis with improvement of symptoms. Pathology showed fibrous and lymphoplasmacytic pleuritis without endometrial tissues seen. Since pleurodesis she has had improvement in dyspnea and size of the pleural effusion. She has been referred to an infertility specialist with no plan as of now for a hysterectomy, although per OB/GYN may be in her future. Obtaining a bloody pleural effusion should include endometriosis related pleural effusion in the differential as it has diagnostic and therapeutic considerations. A meta analysis reviewed a total of 66 individual cases and found that there was poor yield in pleural effusion cytology with increasing diagnostic yield with percutaneous pleural biopsy (45.5%) and surgical lung biopsy (78.7%). Management differed and those who had pleurodesis had a 25% recurrence in comparison to 62% recurrence rate in those just treated with hormonal therapy. The analysis also found that 80% of those with endometriosis-related pleural effusion were infertile. Endometriosis-related pleural effusion therefore remains an important differential for those with bloody pleural effusions in infertile women and has diagnostic and treatment related challenges to be aware of.