Looking at the tip of the iceberg: a case report discussing the diagnosis and management of coexistent diaphragmatic and thoracic endometriosis

Endometriosis is characterized by the presence of endometrial-like glands and/or stroma out of the uterus[ 1 ]. It is estimated to prevail in 10% of reproductive-age women[ 2 ]. While endometriosis is most frequently encountered in the ovaries and uterosacral ligaments [ 3 , 4 ] , extrapelvic localizations of the disease may be encountered in 9–15% of endometriosis patients [ 5 , 6 ] . Diaphragmatic endometriosis is reported to be the most common form of extrapelvic endometriosis[ 5 ]. Reportedly, diaphragmatic endometriosis affects 0.67–4.7% of endometriosis patients [ 7 , 8 ] . On the other hand, the thoracic endometriosis syndrome (TES) is defined by the presence of endometriotic tissue on the diaphragmatic, parietal, or visceral pleura or within the pulmonary parenchyma[ 9 ]. Diaphragmatic endometriosis and TES are often discussed in the literature as two separate entities. However, scattered low-level evidence indicates that diaphragmatic and thoracic endometriosis can be associated in some patients[ 10 ]. The clinical manifestations of thoracic endometriosis are catamenial pneumothorax, catamenial hemothorax, catamenial hemoptysis, and pulmonary nodules[ 11 ]. When it is symptomatic, diaphragmatic endometriosis may cause cyclic shoulder pain or upper abdominal and thoracic pain[ 12 ]. On the other hand, catamenial pneumothorax is sometimes attributed to diaphragmatic endometriosis despite being classically categorized as part of TES. Due to the poor estimation of the coexistence of TES and diaphragmatic endometriosis, solid recommendations regarding the application of video-assisted thoracoscopy (VATS) in patients with diaphragmatic endometriosis are lacking, and the optimal surgical route –whether thoracic, abdominal, or combined – to manage diaphragmatic endometriosis remains questionable. We aim with this work to shed light on the possible correlation between these two entities and the utmost importance of VATS in these patients. We also aim to emphasize that treating diaphragmatic endometriosis alone without exploring the thorax can sometimes result in incomplete excision of endometriosis. This work was done according to the SCARE guidelines[ 13 ].

We intend with this work to highlight the possible association between diaphragmatic and thoracic endometriosis in patients presenting with catamenial pneumothorax. Moreover, we emphasize the role of the multidisciplinary approach to achieve a complete eradication of diaphragmatic and thoracic endometriosis. This case also shows that keeping a high level of suspicion is crucial to detect and effectively treat thoracic endometriosis. The pathophysiology of catamenial pneumothorax is controversial [ 16 , 17 ] . Catamenial pneumothorax in the context of TES is explained by focal defects in the visceral pleura that originate from the necrotic activity of pulmonary endometriotic nodules[ 18 ]. On the other hand, catamenial pneumothorax may be caused by diaphragmatic endometriosis in some patients. It is suggested that air could leak from the abdomen to the thoracic cavity through congenital or endometriosis-associated diaphragmatic fenestrations[ 19 ]. It is thought that the air could reach the abdominal cavity in the menstrual phase due to the liquefication of the cervical mucus plug. The air entry could be provoked by several factors, such as physical activity, sexual intercourse, or abnormal uterine contractions [ 19 , 20 ] . This notion is supported by the simultaneous observation of pneumoperitoneum and pneumothorax in some patients[ 20 ], in addition to endometriotic tissues on the borders of the diaphragmatic fenestrations in others[ 21 ]. Furthermore, diaphragmatic endometriosis was reported in 89% of patients presenting with catamenial pneumothorax[ 22 ]. Another factor that further hardens the decision-making process between laparoscopy, VATS, and a combined abdomino-thoracic approach is the lack of evidence regarding the association between diaphragmatic endometriosis and VATS. A recent study reported that 2.2% of patients with diaphragmatic endometriosis had coexistent thoracic endometriosis[ 23 ]. However, we believe the association rate between these two entities is higher. In another case series, all patients who were re-operated for diaphragmatic endometriosis recurrence were found to have intrathoracic endometriosis[ 10 ]. Several studies have reported on the effectiveness of the surgical approach to treat diaphragmatic endometriosis. In the study of Naem et al [ 12 ], 62.5% of patients were pain-free on the sixth follow-up month. However, this ratio decreased to 50% after 1 year postoperatively. It should be noted that those patients were operated on through conventional laparoscopy, neither robotic-assisted surgery nor VATS was applied[ 12 ]. In the study of Wetzel et al [ 24 ], the recurrence rates were lower, especially in patients who received VATS as primary treatment. It should be noted that the main technique in the study of Wetzel et al [ 24 ] was surgical excision, while surgical ablation was the most common technique as reported in the study of Naem et al [ 12 ]. This variation may be partly responsible for the differences in the resolution rates between the two studies. Nonetheless, both studies reported high rates of patient satisfaction postoperatively, indicating that the surgery is at least effective in reducing the pain intensity if complete pain relief is not achieved [ 12 , 24 ] . Furthermore, the feasibility of robotic-assisted surgery for the management of diaphragmatic endometriosis was demonstrated in the study of D’Ancona et al [ 23 ]. The authors reported that 82.7% of patients reported complete symptom relief at the sixth month of follow-up[ 23 ]. Finally, postoperative hormonal treatment was recommended to reduce the recurrence rate of diaphragmatic and thoracic endometriosis[ 25 ]. In the study of Kim et al [ 26 ], patients who received postoperative hormonal treatments had lower symptom recurrence rates. The same analysis also indicated that patients who received diaphragmatic resection are almost 85% less likely to face recurrences[ 26 ]. The strength of this report is that it visualizes the diaphragm from the abdomen and thorax in addition to following excisional surgical basics. However, it could have benefited from a longer follow-up period.

This report elucidates the safety and effectiveness of VATS and laparoscopic surgery for the treatment of diaphragmatic and thoracic endometriosis in a patient with catamenial pneumothorax. The high level of suspicion remains a key to diagnose and effectively treat diaphragmatic endometriosis and TES, especially in the absence of reliable non-invasive diagnostics.

A 31-year-old G0P0 endometriosis patient presented to the emergency department with a complaint of dyspnea and acute right-sided chest pain. The patient’s symptoms had a spontaneous onset and started in the week preceding her presentation. Six months earlier to her current presentation, the patient received an uncomplicated robotic-assisted excisional surgery for pelvic endometriosis, during which diaphragmatic endometriosis was spotted. Pelvic endometriosis was confirmed by the histopathologic examination. The intraoperative #Enzian classification[ 14 ] was as follows: P0, O1/1, T3/3, A3, B2/2, C3, FI ( sigmoid colon ), and F (diaphragm). After 2 months of the robotic-assisted surgery, the patient opted for a levonorgestrel-releasing intrauterine device (LNG-IUD) due to the persistence of the irregular menstrual bleeding. According to the revised classification of the American Society of Reproductive Medicine[ 15 ], the corresponding endometriosis stage was stage IV. Rectal and sigmoid endometriosis were treated by shaving. However, diaphragmatic endometriosis was left in situ at that time because it was not preoperatively suspected, and the patient received colorectal surgery. Therefore, the surgeon decided to leave the diaphragmatic lesions in situ as a precaution for any pelvic infection that could spread to the thorax. The patient received a high-resolution computed tomography scan (HRCT) that revealed a moderate right-sided pneumothorax. The HRCT also demonstrated a complete collapse of the upper and middle lobes and a partial collapse of the lower lobe of the right lung. Consolidation of the right upper and middle pulmonary lobes was spotted. Based on these findings and the patient’s gynecologic history, TES was suspected to be the underlying cause of the pneumothorax. However, a bronchoscopy was performed to rule out any pathology that may have contributed to the patient’s symptoms. The bronchoscopy was unremarkable and confirmed the collapse of the upper and lower lobes of the right lung. On this basis, a provisional diagnosis of TES was established. After careful discussion with the patient and a thoracic surgeon, multidisciplinary surgical management was agreed on. Under general anesthesia, the patient was positioned in the dorsal lithotomy. Then, pneumoperitoneum was achieved. A 10-mm working trocar was inserted 4 cm under the xiphoid process of the sternum through the direct entry method. Thereafter, the patient was placed in the steep reversed Trendelenburg position. The ancillary trocars were placed under direct visualization. A 5-mm port was placed in the right mid-axillary line at the level of the umbilicus, and another 5-mm trocar was placed between the previous two ports. Upon inspection of the diaphragmatic domes, superficial endometriotic lesions on the right hemidiaphragm were spotted. In addition, adhesions between the right diaphragmatic dome and the hepatic capsule were noted (Fig. 1 ). The surgical intervention was started with the dissection of the falciform ligament. Adhesiolysis between the diaphragm and the hepatic capsule was performed. The right-sided endometriotic lesions were excised with a harmonic scalpel. Figure 1. The laparoscopic appearance of diaphragmatic endometriosis via laparoscopy. (A) The small diaphragmatic lesions on the right diaphragmatic dome (yellow circle) with minor adhesions. (B) The pericapsular hepatic adhesions between the left hepatic lobe and the left diaphragmatic dome. HIGHLIGHTS Diaphragmatic and thoracic endometriosis may coexist. Minor diaphragmatic endometriosis may hide a more severe thoracic endometriosis. An abdomino-thoracic approach may be crucial for complete endometriosis excision. The joint surgical approach is safe and effective when it is correctly indicated. The laparoscopic appearance of diaphragmatic endometriosis via laparoscopy. (A) The small diaphragmatic lesions on the right diaphragmatic dome (yellow circle) with minor adhesions. (B) The pericapsular hepatic adhesions between the left hepatic lobe and the left diaphragmatic dome. Diaphragmatic and thoracic endometriosis may coexist. Minor diaphragmatic endometriosis may hide a more severe thoracic endometriosis. An abdomino-thoracic approach may be crucial for complete endometriosis excision. The joint surgical approach is safe and effective when it is correctly indicated. Afterward, VATS was started. Upon reaching the thoracic cavity, a hemorrhagic pleural effusion of around 100 ml and extensive endometriosis of the diaphragm and the parietal pleura were observed (Fig. 2 and Fig. 3 ). The endometriotic lesions of the diaphragm were treated by the mean of full-thickness diaphragmatic resection. The diaphragmatic defect was closed with a V-lock suture (Fig. 4 ). Thereafter, an apical pleurectomy was performed to remove the endometriotic lesions of the parietal pleura. Eventually, complete lung expansion was achieved, and talc pleurodesis was performed. At the end of the operation, the diaphragm was inspected laparoscopically to ensure a good diaphragm closure. The LNG-IUD was retained postoperatively. No complications occurred intra- or postoperatively. Figure 2. Video-assisted thoracoscopy revealed more extensive diaphragmatic endometriosis and scar tissue on the right diaphragmatic dome with hemorrhagic pleural effusion. Figure 3. Endometriosis of the apical pleura (yellow circles). Figure 4. Full-thickness resection of the diaphragm. Video-assisted thoracoscopy revealed more extensive diaphragmatic endometriosis and scar tissue on the right diaphragmatic dome with hemorrhagic pleural effusion. Endometriosis of the apical pleura (yellow circles). Full-thickness resection of the diaphragm. After 6 months of follow-up, the patient reported a complete symptom resolution. During the follow-up period, the patient did not have recurrent episodes of spontaneous pneumothorax.