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Right Middle Lobe Syndrome Clinical Presentation

  • Author: Nemr S Eid, MD, FAAP, FCCP; Chief Editor: Michael R Bye, MD  more...
Updated: Apr 17, 2015


The most common symptoms in right middle lobe syndrome (RMLS) include the following:

  • Persistent or recurrent cough
  • Intermittent wheezing
  • Dyspnea
  • History of recurrent or chronic pneumonia (May often be a misinterpretation of the radiographic findings)

In many cases, these respiratory symptoms are refractory to normal treatment.

At least half of the patients report a history of asthma or atopy, and one third report a family history of atopy.

Less frequently reported symptoms, which may be indicative of chronic disease with suppurative complications, include the following:

  • Hemoptysis
  • Low-grade fever
  • Fatigue
  • Weight loss
  • Chest pain


Right middle lobe syndrome is essentially a radiographic diagnosis, and physical findings widely vary.

Auscultation of the lungs may reveal a fine wheeze, rales, or diffuse rhonchi, ranging from decreased aeration and dullness to percussion in the region of the right middle lobe. The right middle lobe is anterior, best heard at the nipple. The medial segment is located medial to the nipple; the lateral segment is lateral to the nipple. Failure to listen to this area results in failure to hear the right middle lobe.

Clubbing is rarely found in patients with advanced disease.



Intra-airway origin

In children, right middle lobe syndrome is usually secondary to primary ventilation disorders. Chronic inflammation of the airways, which contributes to atelectasis of the right middle lobe, is present. A paucity of collateral ventilation is observed in children and serves to prevent reinflation.

Primary disorders of ventilation include the following:

Airway foreign body aspiration include the following:

  • Endobronchial tumors
  • Mucous plugging, as from any of the above
  • Granulation tissue

Extra-airway origin

Extraluminal compression is caused by the following:

  • Cardiovascular anomalies
  • Congenital malformations such as situs inversus and other anatomical defects such as anomalous branching or abnormal diameter, length, or structure of the bronchi
  • Lymphadenopathy of peribronchial nodes
  • Tumors
  • Traction diverticula of the esophagus

Infectious etiologies

See the list below:

  • Whether the infection is a cause of the collapse or a result of airway stasis and poor clearance may not be clear.
  • Primary infectious etiology is more frequent in adults; however, one pediatric study found that 50% of children with collapsed right middle lobe had an underlying bacterial infection.[1]
  • Infectious causes also increase in frequency among immunocompromised patients.
  • Common bacterial causes in children include Streptococcus pneumoniae and Haemophilus influenzae.
  • Fungal causes include histoplasmosis, blastomycosis, and aspergillosis, which manifest as allergic bronchopulmonary aspergillosis (APBA).
  • Mycobacteria, including Mycobacterium tuberculosis, Mycobacterium avium-intracellulare, and Mycobacterium fortuitum have also been identified as causal agents.
  • Occurrence is mainly caused by extrinsic compression by hilar lymph nodes, which are commonly observed in these infections as well as in fungal infections.
Contributor Information and Disclosures

Nemr S Eid, MD, FAAP, FCCP Professor of Pediatrics, University of Louisville School of Medicine; Director of Pediatric Pulmonary Medicine, Director of The Childhood Asthma Care and Education Center and the Cystic Fibrosis Center, Medical Director of Pediatric Respiratory Therapy, Kosair Children's Hospital

Nemr S Eid, MD, FAAP, FCCP is a member of the following medical societies: Kentucky Chapter of The American Academy of Pediatrics, Kentucky Pediatric Society, American College of Chest Physicians, American Thoracic Society, Kentucky Medical Association

Disclosure: Nothing to disclose.


Michelle Eckerle University of Louisville School of Medicine

Michelle Eckerle is a member of the following medical societies: Kentucky Medical Association

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Chief Editor

Michael R Bye, MD Professor of Clinical Pediatrics, State University of New York at Buffalo School of Medicine; Attending Physician, Pediatric Pulmonary Division, Women's and Children's Hospital of Buffalo

Michael R Bye, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Chest Physicians, American Thoracic Society

Disclosure: Nothing to disclose.

Additional Contributors

Thomas Scanlin, MD Chief, Division of Pulmonary Medicine and Cystic Fibrosis Center, Department of Pediatrics, Rutgers Robert Wood Johnson Medical School

Thomas Scanlin, MD is a member of the following medical societies: American Association for the Advancement of Science, Society for Pediatric Research, American Society for Biochemistry and Molecular Biology, American Thoracic Society, Society for Pediatric Research

Disclosure: Nothing to disclose.


Heidi Connolly, MD Associate Professor of Pediatrics and Psychiatry, University of Rochester School of Medicine and Dentistry; Director, Pediatric Sleep Medicine Services, Strong Sleep Disorders Center

Heidi Connolly, MD is a member of the following medical societies: American Academy of Pediatrics, American Thoracic Society, and Society of Critical Care Medicine

Disclosure: Nothing to disclose.

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Posteroanterior chest radiograph demonstrating right middle lobe collapse and infiltrate. Note blurred right heart border.
Lateral view chest radiograph showing a wedge-shaped density extending from the hilum anteriorly and inferiorly.
Chest CT scan showing extensive bronchiectasis of both medial and lateral segments of the right middle lobe.
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