Thoracic endometriosis

Thoracic endometriosis or Thoracic Endometriosis Syndrome (TES) is a rare form of endometriosis where endometrial tissue is found in the lung parenchyma and/or the pleura. It can be classified as either pulmonary, or pleural, respectively.^[1]

Epidemiology

Thoracic endometriosis affects women aged 15–54, who are between menarche and menopause. It can affect their qualify of life, with catamenial pneumothorax being the most common presentation.^[1]

Pathophysiology

Endometrium, the tissue that normally lines the female uterus, undergoes changes with each menstrual cycle. At the end of each cycle, after the lining has built up in preparation for hosting a fertilised ovum, it decays, detaches, and is expelled through the cervix and vagina in the form of a period. In endometriosis, this tissue is found in other parts of the female body; commonly the pelvis and abdomen, but rarely in the thorax (as in thoracic endometriosis), the central nervous system, the nasal passages, or the skin. At these other 'ectopic' sites, endometrium still responds to hormones with normal cyclical changes - bleeding roughly every 28 days.

It is widely held that intraabdominal and pelvic endometriosis is due to retrograde menstruation, where menstrual debris may flow up the fallopian tubes instead of out the cervix and vagina; this seeds endometrial tissue onto the peritoneum. This does not, however, explain the rare cases in which endometrial tissue is deposited or develops above the diaphragm. Theories explaining distant ectopic endometriosis include:

• Vasculogenesis: Up to 37% of the microvascular endothelium of ectopic endometrial tissue originates from endothelial progenitor cells, which result in de novo formation of microvessels by the process of vasculogenesis rather than the conventional process of angiogenesis.^[2]
• Lymphatic spread: endometrial fragments travel through the thoracic duct and hilar lymph nodes, reaching the chest cavity and causing pulmonary or pleural endometriosis.^[3]
• Coelomic metaplasia theory: the pleura and peritoneum share the same embryological origin, both derived from mesothelium. A pathological stimulus could be responsible for inducing precursor cells (mesothelial stem cells) of the pleura or peritoneum in order to differentiate into endometrial cells.^[3]
• Vascular embolisation: endometrial fragments are taken into the venous system, travel through the right side of the heart, and are deposited in the pulmonary circulation. The endometrial tissue settles in the lung parenchyma or pleura.^[3]

A review of autopsy data showed that patients with endometriosis have bilateral pulmonary lesions, which supports the vascular embolisation theory. The pleural and/or diaphragmatic lesions were always found on the left side, which supports the theory of coelomic metaplasia.

Aetiology

The aetiology of thoracic endometriosis is unknown.^[4] Patients with multiple previous operations are more prone, due to the manipulation that may cause embolisation of the endometrial tissue into the thoracic cavity. Some thoracic endometriosis patients have been described as having a congenital defect in the diaphragm. There is also an association between thoracic and pelvic endometriosis.

Symptoms

Thoracic endometriosis is characterised by onset of the following clinical situations within 72 hours of the onset of menses.

• Catamenial pneumothorax: this is the most common clinical manifestation, present in 80% of cases. Catamenial pneumothorax is defined as a recurrent pneumothorax that occurs within the first 72 hours after menstruation. It may not necessarily occur with every menstrual cycle and in most cases is one-sided and left side. There are particular cases of catamenial pneumothorax on the right side, and on very rare occasions there may be a bilateral catamenial pneumothorax. Symptoms are the same as for any other pneumothorax: chest pain, cough and breathlessness. Symptoms are usually mild but there may be severe presentations.^[5]
• Catamenial hemothorax: this is a rare manifestation of thoracic endometriosis, occurring in 14% of cases. Almost always, the right side is involved but has reported one case of a bilateral catamenial hemothorax. The most common presenting symptoms are nonspecific and include cough, chest pain and shortness of breath. In some cases, signs may mimic pulmonary embolism. The quantity of blood loss varies, but severe anemia is possible. In almost all cases, chest x-ray shows the presence of pleural effusion without specific characteristics. A CT scan may show additional features such as nodular lesions of the pleura, multiloculated effusions, or bulky pleural masses.^[5]
• Cyclic haemoptysis: haemoptysis during menstruation is extremely rare, with about 30 case reports in medical literature.^[6] Currently, there have been no reports of massive haemoptysis or death. Cyclic haemoptysis is a sign of pulmonary parenchymal endometriosis; ectopic endometrial tissue in the lung responds to cyclical hormonal variation, bleeding along with the normal endometrium located in the uterus.^[5]
• Pulmonary nodules: nodules are common radiological features in patients with thoracic endometriosis; most cases are associated with catamenial haemoptysis.

Apart from the previously mentioned clinical manifestations, the patient may suffer from dysmenorrhoea and irregular menses.^[7]

Complications

Pneumothorax and haemothorax are discussed above, and are rarely life threatening. Otherwise, the most common complication is progressive tissue damage or scarring related to inflammation, and in extremely rare cases malignant transformation of the endometrial tissue.^[1]

Diagnosis

The diagnosis of thoracic endometriosis is primarily based on clinical history and examination, augmented with non-invasive studies such as X-ray, CT scan, and magnetic resonance imaging of the chest. Pelvic ultrasound is also useful to determine if the patient has any degree of pelvic or abdominal endometriosis (indicated by the presence of free fluid). More invasive methods for obtaining a tissue diagnosis of thoracic endometriosis include video thoracoscopy (for pleural or pulmonary biopsy), or bronchoscopy (for pulmonary or bronchial biopsy, or bronchial lavage).^[5] A case series has been reported in which clinical diagnosis was made in 50% of patients, the rest being diagnosed either via biopsy (25%) or bronchoalveolar lavage (25%). (25%)

Treatment

Clear diagnosis is useful to avoid unnecessary treatment and exclude more sinister diagnoses (for example, haemoptysis or pleural effusion could also indicate cancer). Overall treatment for pulmonary endometriosis is surgical, with subsegmentectomy. It is obviously important to preserve as much lung parenchyma as possible, while removing macroscopic signs of pathological tissue.^[4] Medical treatment includes gonadotropin-releasing hormone analogues, which can cause cessation of menstruation and decreased libido, as well as a 50% recurrence rate.^[8][9] Even in the asymptomatic, treatment is recommended to prevent possible complications listed above.

References

1. Rojas, J. (2014). Endometriosis pulmonar parenquimal. Rev Soc Peru Med Interna, 27(1).
2. Laschke MW, Giebels C, Menger MD (2011). "Vasculogenesis: a new piece of the endometriosis puzzle". Hum. Reprod. Update. 17 (5): 628–36. doi:10.1093/humupd/dmr023. PMID 21586449.
3. Endometriosis parenquimatosa pulmonar multifocal.Patologia, 262-266
4. Endometriosis pulmonar torácica: presentación de 2 casos de una enfermedad muy poco frecuente | Archivos de Bronconeumología http://www.archbronconeumol.org/es/thoracic-pulmonary-endometriosis-two-reports/articulo/S030028961300358X/
5. Alifano, M. (n.d.). Thoracic Endometriosis: Current Knowledge. Retrieved July 7, 2016, from http://www.annalsthoracicsurgery.org/article/S0003-4975(05)01322-6/fulltext?refuid=S0003-4975(11)02531-8&refissn=0003-4975
6. McGraw-Hill Medical| AccessMedicine | McGraw-Hill Medical http://accessmedicine.mhmedical.com/content.aspx bookid=331
7. U.S National Library of Medicine https://www.nlm.nih.gov/medlineplus/spanish/ency/article/000915.htm
8. http://www.elsevier.es/es-revista-progresos-obstetricia-ginecologia-151-articulo-neumotorax-catamenial-recurrente-13067055
9. Korean J Obstet Gynecol. 2012 Dec;55(12):1031-1034. Korean. Published online Dec 18, 2012. http://dx.doi.org/10.5468/KJOG.2012.55.12.1031