A Case of Catamenial Pneumothorax Treated by Video- Assisted Thoracoscopic Surgery

Although there is no consistent view regarding a mechanism for the occurrence of catamenial pneu- mothorax, there are 3 hypotheses: the intraperi- toneal air theory (Maurer et al., 1958), the subpleu- ral endometrial implant theory (Lillington et al., 1972) and the prostaglandin F2α theory (Rossi and Goplerud, 1974). As for the intraperitoneal air the- ory, it is assumed that air entering the abdominal cavity through the uterine and fallopian tubes at the time of menstruation could enter the thorax through a defective pore due to diaphragmatic endometrio- sis, and thus cause a pneumothorax (Maurer et al., 1958). In our patient, because small fenestrations were found in the right diaphragm and pneumotho- rax was not found in the lung, this hypothesis is considered highly likely. Histologically, although no endometrial tissue was found in the diaphragm, the tissue might have fallen out, causing formation of the small pore (Shiraishi, 1991). This disease was diagnosed as catamenial pneumothorax before surgery, because it was right pneumothorax in a middle-aged female and the symptoms repeated around the start of her men- struation. Presence of the diaphragmatic fenestra- tions, as an intraoperative finding, and her having a normal lung, created a relatively certain diagnostic basis. After surgery, hormonal therapy was started and pneumothorax did not recur during that period. Fig. 2. The excised diaphragm showing the perforation penetrating the intraperi- toneum. The scale indicates 1 cm. 28 S. Yasui et al. Four months after the treatment was stopped, right pneumothorax recurred in accordance with the start of her menstruation. From the positive effects of the hormonal therapy, it was again highly possible that this case was a catamenial pneumothorax. Treatments for this patient focused on surgical and hormonal therapies. Indication for therapy de- pended on the severity and frequency of the pneu- mothorax, age and patient’s desire for pregnancy. Surgical therapy included closure of the diaphrag- matic fenestration and pleural symphysis, with the frequent use of VATS. However, the recurrence rate of cases in which diaphragmatic lesions were excised is high, 21% (Banba et al., 1983). In our patient, because a large number of preliminary le- sions were observed in the diaphragm during sur- gery, the recurrence after surgery may have been due to a new fistula occurring at another site on the diaphragm. However, this surgery is used normally when the pneumothorax is causing the problem, yet may simultaneously be a very useful method for creating a diagnostic standard for discounting natu- ral pneumothorax due to bulla, observation of dia- phragmatic defective pores and allopatric endo- metriosis in the pleura (Inagaki et al., 1999). Hormonal therapy follows drug treatment for endometriosis, including testosterone derivatives, Gn-RH agonists and oral contraceptives (Slabbynck et al., 1991). However, it is difficult to continue this therapy because of the appearance of side effects (Banba et al., 1983), and because when it is stopped, the symptoms recur; thus this therapy has not been established as a complete treatment method. To es- tablish a more effective treatment method, it will be necessary to elucidate endometriosis as a prognos- tic background as well as other related pathologic conditions.

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