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.
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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.
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:
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. 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 24 hours prior to and 72 hours after onset of menses.
Apart from the previously mentioned clinical manifestations, the patient may suffer from dysmenorrhoea and irregular menses.
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.
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). 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. Medical treatment includes gonadotropin-releasing hormone analogues, which can cause cessation of menstruation and decreased libido, as well as a 50% recurrence rate. Even in the asymptomatic, treatment is recommended to prevent possible complications listed above.