Catamenial pneumothorax occurs in women of child-bearing age and, by definition occurs within 72 hours before or after the onset of menstruation. Pneumothorax may be recurrent and there may be a history of pelvic endometriosis. Around 90% of pneumothoraces occur on the right.
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Epidemiology
The diagnosis is not often considered and the true frequency is unknown. One study reports that 24% of 229 consecutive women of reproductive age undergoing surgery for pneumothorax were diagnosed with thoracic endometriosis on histology 8. 50% of catamenial pneumothoraces and 6% of non-catamenial pneumothoraces had thoracic endometriosis on histology 8.
Women most frequently present in their 30s and 40s. Recurrent catamenial pneumothorax has been reported in a 14 year old with no VATS evidence of thoracic endometriosis 15 .
Diagnosis
The diagnosis can be made in women of reproductive age who present with pneumothorax within 72 hours of the onset of menstruation.
Clinical presentation
Pneumothorax typically presents with chest pain, sometimes with dyspnea. Around 90% occur on the right.
Pathology
Catamenial pneumothorax can be caused by thoracic endometriosis. Diaphragmatic endometrial deposits are commonly seen at laparoscopy for pelvic endometriosis and the clockwise circulation of peritoneal fluid may explain the strong right-sided predilection. Cyclical proliferation and necrosis of endometrial deposits may perforate the diaphragm 14. Fenestrations in the tendinous portion of the diaphragm are visible at VATS and transdiaphragmatic spread may explain the predilection for intrathoracic diaphragmatic deposits.
Diaphragmatic and the less common visceral pleural deposits may fluctuate in size during the menstrual cycle. At histology, endometrial stroma with positive estrogen and progesterone receptors and positive CD10, (see case 4) may be accompanied by hemosiderin-laden macrophages.
Elevated serum titer of Ca125 antigen may be a helpful indicator of endometriotic disease 14.
Other theories have been proposed to explain catamenial pneumothorax:
passage of air from the uterus into the peritoneal cavity and through diaphragmatic fenestrations
alveolar rupture precipitated by bronchoconstriction due to prostaglandin F2
vascular microembolisation of endometrial tissue 14
Radiographic features
Although pneumothoraces are approximately 90% right-sided, left-sided pneumothoraces and synchronous or metachronous bilateral pneumothoraces can occur 7,10,11. Hemopneumothorax is also reported.
Plain radiograph
Imaging features are often identical to pneumothoraces from other causes although adhesions may be apparent and pneumoperitoneum may coexist.
Nodules of endometriosis may be too small to identify. Larger nodules may be seen along the diaphragm or on the visceral pleura. One case report retrospectively identified small diaphragmatic air bubbles 16.
CT
CT is a more sensitive technique to demonstrate the above findings, including small nodules and defects. Occasionally part of the liver may herniate through a larger diaphragmatic defect (collar sign) 7.
MRI
MRI may suggest pleural-based masses attributable to endometrial implants 7.
Treatment and prognosis
Most catamenial pneumothoraces are small and self-resolving. VATS treatment of thoracic endometriosis includes partial diaphragmatic resection and repair, excision of all visceral pleural implants and talc pleurodesis. This is followed by hormone therapy to lessen the chance of recurrence which can be as high as 40% 14. Continuous administration of the oral contraceptive pill causes atrophy of the endometrium and avoids cyclic proliferation and necrosis of endometrial deposits.
History and etymology
It was initially described in 1958 by Maurer 7. The term 'catamenial' was coined by Lillington in 1972 9. It is derived from the Greek words pertaining to and monthly 2,10.
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