Description, Causes and Risk Factors:
Atelectasis with chronic pneumonitis of the middle lobe of the (right) lung, due to compression of the middle lobe bronchus, usually by enlarged lymph nodes, which may be tuberculous; chief symptoms are chronic cough, wheezing, recurrent respiratory infections, hemoptysis, chest pain, malaise, easy fatigability, and loss of weight; sometimes confused with interlobar accumulation of fluid in the lateral x-ray view.
Brock syndrome is defined as recurrent or chronic collapse of the middle lobe of the right lung. It can be divided into an obstructive type, such as obstruction related to malignancy or infection, and a non-obstructive type with a patent airway.
Obstructive middle lobe syndrome can be caused by endobronchial lesions or extrinsic compression of the right middle lobe bronchus. Malignancy is the most common cause of the obstructive type. Extrinsic compression is most commonly due to peribronchial lymphadenopathy which can be caused by infection, such as mycobacteria, metastatic neoplasm and sarcoidosis. Rare causes of obstruction include broncholiths, aspirated foreign body and inspissated mucus associated with cystic fibrosis.
Non-obstructive type of middle lobe syndrome, which occurs in about one-half of .patients, is associated with bronchiectasis, asthma, recurrent pneumonia and bronchitis. It is postulated that the poor collateral drift in the middle lobe impairs the clearing of mucus plug and predisposes to chronic inflammation and collapse. Pathologically there may be bronchiectasis, chronic bronchitis with lymphoid hyperplasia organizing pneumonia, and abscess formation.
Classically, the Brock syndrome has been described as being caused by a central obstruction. Clinical records and radiologic findings were reviewed in 129 patients examined between 1955-1981 who had chronic disease in the right middle lobe and/or lingula. Fifty-eight patients (45%) had no evidence of a central obstructive lesion. The majority were middle-aged women with histories of chronic cough and chest pain. Bronchoscopic and radiologic evaluation served to exclude central lesions. Surgical confirmation was available in 38 patients. Pathologic study showed varying degrees of chronic inflammation, pneumonia, and bronchiectasis. Surgical results were excellent in isolated disease. Chronic atelectasis and pneumonitis of the right middle lobe and/or lingula do not always imply central obstruction. A lack of collateral ventilation is a plausible theory to explain the pathophysiology in such patients.
Clinically most patients are symptomatic with intermittent or recurrent cough, hemoptysis, chest pain, wheezing, and fever and chills. Rarely it can be asymptomatic.
Differential diagnosis may include:
Chronic granulomatous disease.
Primary humoral immunodeficiency disorder.
Immotile cilia syndrome.
Diagnosis is made by radiologic findings,where there is right edge blurring of the heart inthe posteroanterior view and a shadow that isgenerally triangular in shape extending from theposterior edge to the anterior chest wall in thelateral view.
Radiologically the atelectatic middle lobe is easy to overlook on posteroanterior (PA) chest radiograph but is readily recognizable on the lateral chest radiograph. PA chest radiograph demonstrates blurring of the right heart border (silhouette sign). The lateral view will demonstrate a triangular area of increase in density between the minor and major fissure. At computed tomographic (CT) scan, the right middle lobe atelectasis appears as a triangular density bounded posteriorly by the major fissure, medially by the right heart border, and anteriorly by the minor fissure. CT scan can evaluate for bronchial patency, lymph node enlargement and calcification, or other extrinsic compression of the right middle lobe airway.
Long-term follow-up of children with right Brock syndrome shows that most patients do not experience recurrent or persisting symptoms. This indicates that the first line of treatment in all cases is conservative medical management, except in cases involving neoplastic origin and those with bronchiectasis.
Chest physical therapy and postural drainage are the hallmarks of therapy.
Treat the asthmatic child with aggressive anti-inflammatory therapy such as inhaled steroids. Consider systemic steroids. Guidelines for the diagnosis and management of asthma have been established.
Provide the patient with chest physical therapy and postural drainage. In unresponsive patients or patients who have a predisposition to airway colonization, an appropriate antibiotic, as determined by a bronchoalveolar lavage (BAL) culture, should be added to their regimen.
Patients with fungal infections (e.g., histoplasmosis) or tuberculous infections who have hilar adenopathy and complete blockage of their right middle lobe should be treated aggressively. The addition of systemic corticosteroids may be necessary.
Surgical Options: Lobectomy is indicated in cases of malignancy and bronchiectasis that are unresponsive to medical therapy.
Only perform lobectomy when right middle lobe syndrome is associated with systemic symptoms such as failure to thrive, persistent cough, and recurrent fever or when chronic infection threatens the remainder of the lung.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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