A chocolate effusion – An unusual cause of elevated adenosine deaminase in the pleural fluid

BACKGROUND: Thoracic Endometriosis Syndrome (TES) is a rare diagnosis characterized by ectopic endometrial tissue in the chest. Pleural fluid adenosine deaminase (ADA) is thought to be highly specific for tuberculous pleural effusions, particularly when >40 IU/L (international units/liter). RESULTS: A 36-year-old woman from Cameroon (immigrated 10 years ago) with no past medical history presented to the emergency department with increasing abdominal swelling over months found to have on imaging ascites, a left adnexal lesion, a large right-sided pleural effusion and peritoneal studding. Sampling of the pleural fluid revealed dark brown fluid which on analysis was a non-specific exudate with an adenosine deaminase >100. Exploratory laparotomy by gynecology-oncology revealed a large amount of hemorrhagic ascites, multiple endometriotic implants, and a right ovarian endometrioma. Ultimately the patient was taken for video-assisted thoracoscopy (VATS) and decortication. The VATS revealed a diaphragmatic tear was seen suggesting the etiology of the pleural fluid was trans-diaphragmatic passage of blood through the defect. There was no evidence of malignancy or granulomas. Stains and subsequent cultures were negative on all specimens for Mycobacterium tuberculosis. DISCUSSION: Our case demonstrates a rarity of an ADA >100 IU/L due to TES rather than tuberculosis. In conclusion, ADA analysis, as with any lab test, should be interpreted within clinical context as false positives may occur. Several weeks following presentation the patient was discharged without any intrapleural catheter and near complete expansion of the lung. She was started on leuprolide and medroxyprogesterone and has no recurrent effusion or ascites in over two years since initial presentation.