Right Middle Lobe Syndrome Workup

Updated: May 16, 2018
  • Author: Nemr S Eid, MD, FAAP, FCCP; Chief Editor: Denise Serebrisky, MD  more...
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Laboratory Studies

The following studies may be indicated in right middle lobe syndrome (RMLS):

  • Purified protein derivative (tuberculin) skin test

  • CBC count and differential

  • Westergren sedimentation rate

  • Fungal serology by complement fixation and immune diffusion

  • Quantitative immunoglobulins panel


Imaging Studies

Chest radiography with anteroposterior (AP) and lateral views

The classic finding of right middle lobe syndrome is a blurred right heart border and a loss of volume in the right middle lobe (see the image below).

Posterioranterior chest radiograph demonstrating r Posterioranterior chest radiograph demonstrating right middle lobe infiltrate in a 9-year-old male with a history of severe asthma. Note the blurred right heart border.

A wedge-shaped density extending from the hilum anteriorly and inferiorly is best visualized on a lateral view (see the image below).

Lateral view chest radiograph in a 9-year-old male Lateral view chest radiograph in a 9-year-old male with severe asthma showing a wedge-shaped density extending from the hilum anteriorly and inferiorly.

Consolidation and infiltration are less commonly observed.

Acute pneumonia should clear radiologically in 6-8 weeks.

CT scanning

If bronchiectasis is suspected, confirm diagnosis by performing high-resolution chest CT scanning (see the image below), which carries less risk to younger patients or patients with asthma than the seldom-used traditional bronchography. Chest CT scans may also be beneficial in providing information on airway patency and sources of extrinsic compression. [3]  

High-resolution chest CT showing marked chronic ch High-resolution chest CT showing marked chronic changes and volume loss in the right middle lobe with diffuse traction bronchiectasis in 9-year-old male with a history of severe asthma and RML syndrome.

High-resolution chest CT imaging is also helpful for follow-up medical therapy.


Other Tests

Pulmonary function tests (PFTs) can be used to establish a previously unidentified asthmatic component.

When assessing for asthma, a patient's baseline forced expiratory volume in one second (FEV1) may be normal on spirometry.  However, a post-bronchodilator test demonstrating a 10-15% improvement in FEV1, or 25% or greater improvement in FEF25-75% is diagnostic for asthma. [4] In these cases, patients should be treated aggressively per established asthma guidelines.

A study evaluating the usefulness of lung ultrasonography for the diagnosis of neonatal pulmonary atelectasis (NPA) concluded that lung ultrasonography is an accurate and reliable method for diagnosing NPA. This was a study solely in infants. The authors also concluded that lung ultrasonography can find occult lung atelectasis in neonates that could not be detected on chest X-ray. [5]



The value of bronchoscopy is 2-fold, as follows:

  • It is immediately therapeutic in removing mucus and clearing the airway and can be curative in some cases.

  • It allows visualization of the airway and the ability to determine patency of the right middle lobe bronchus and to discern whether endobronchial obstruction is the cause.

Bronchoalveolar lavage can be concurrently performed to determine cellular elements in the right middle lobe. It can also be used to assess the presence of infections by culturing and staining for bacterial, fungal, viral, and mycobacterial pathogens.