Middle Lobe Syndrome: A Review of Clinicopathological Features, Diagnosis and Treatment

Abstract

Middle lobe syndrome (MLS) is a rare but important clinical entity that has been poorly defined in the literature. It is characterized by recurrent or chronic collapse of the middle lobe of the right lung but can also involve the lingula of the left lung. Pathophysiologically, there are two forms of MLS, namely obstructive and nonobstructive. Obstructive MLS is usually caused by endobronchial lesions or extrinsic compression of the middle lobe bronchus such as from hilar lymphadenopathy or tumors of neoplastic origin, resulting in postobstructive atelectasis and pneumonitis. In the nonobstructive type, no obstruction of the middle lobe bronchus is evident during bronchoscopy or with computerized tomography of the chest. The etiology of the nonobstructive form is not completely understood. Inefficient collateral ventilation, infection and inflammation in the middle lobe or lingula are thought to play a role, and bronchiectasis is the most common histological finding. Patients with proven endobronchial lesions or malignancy are usually offered surgical resection directly. This contrasts with nonobstructive MLS, where most patients respond to medical treatment consisting of bronchodilators, mucolytics and broad-spectrum antibiotics. However, some patients do not respond to conservative treatment and may suffer irreversible damage of the middle lobe or lingula, in addition to having recurrent symptoms of infection or inflammation. These selected patients can be offered surgical resection of the middle lobe or lingula, which is associated with a low mortality rate and favorable outcome.

Ten Years’ Experience in Surgical Treatment of Right Middle Lobe Syndrome

“…The clinical symptoms that our patients had were cough, sputum, hemoptysis, chest pain and history of treatment for recurrent pneumonia, a similar finding to most other studies. 6,7,8) We found that our patients were younger than cases in Kwon 9) study (with the mean age of 47 years) and Einarsson's 7) cases (mean age of 55.7 years), but older than patients of Meteroglu 10) study with the mean age of 12.3 years.…”

“…8) Plain chest radiographies may show broncho stenosis, right middle lobe collapse, inflammatory changes, and bronchiectasis. The radiographic findings most often seen in our study were atelectasis, collapse, and bronchiectasis which the last one were more than the rate of previous studies, and our broncho stenosis cases were less.…”

“…The narrow diameter of the middle lobe bronchus and the acute take-off angle besides the relative anatomical isolation of the middle lobe create poor conditions for drainage. 7,8) Also, it was previously reported that swelling of lymph nodes in response to either acute or chronic inflammation can narrow the bronchus and cause atelectasis, chronic bronchitis, or bronchiectasis which can gradually lead to collapse and narrowing of the bronchial divisions. In addition, the middle lobe contains only scanty paranchymal bridges due to the deep fissures that isolate this lobe which provides barriers to collateral ventilation.…”

Lady Windermere syndrome

“…27 The bronchi in the middle lobe have small diameters and lack collateral ventilation making clearance of secretions difficult without expectoration. [37][38][39] This idea is supported by a case series which showed that voluntary cough suppression could lead to cylindrical bronchiectasis. 40 However, evidence for cough suppression prior to developing LWS is limited to case reports.…”

Intrinsic Endobronchial Obstructions in Children from Turkey: Evaluation of 2,555 Flexible Bronchoscopic Procedures

“…Diagnosis and treatment of endobronchial obstructions can be challenging depending on the etiology. These obstructions can be diagnosed best by flexible bronchoscopy (FB) in order to directly view the pathology and, when indicated, perform a biopsy [12,13]. …”