Catamenial haemothorax-A rare cause of pleural effusion.

Common causes of haemorrhagic pleural effusions include malignancy (primary or metastatic), tuberculosis, pulmonary embolism, collagen vascular diseases, trauma and iatrogenic causes. Clinical history along with pathologic, microbiologic and biochemical evaluation of pleural fluid confirms the diagnosis in most cases. However, if there is recurrent haemorrhagic effusion without corroborative history or mass lesion in lung, or evidence of microorganisms, then we should think of uncommon causes. Catamenial haemothorax (CHt) is a rare cause of haemorrhagic pleural effusion, which recurs during each menstrual cycle. This is a manifestation of thoracic endometriosis syndrome (TES) caused by ectopic endometrial tissue in the thoracic cavity in women of child-bearing age. This extremely rare condition is difficult to diagnose, unless direct correlation with the menstrual cycle is established. TES consists of pleural forms such as catamenial pneumothorax, non-catamenial endometriosis-related pneumothorax and haemothorax; and parenchymal forms such as catamenial haemoptysis and lung nodules. Here we report a case of CHt in a 43-year-old female whose diagnosis was established by thoracoscopic pleural biopsy.