Right Middle Lobe Syndrome


Article Author:
Umair Shaikh


Article Editor:
Daniel Heller


Editors In Chief:
Sisira Reddy
Joseph Nahas
Chokkalingam Siva


Managing Editors:
Avais Raja
Orawan Chaigasame
Khalid Alsayouri
Kyle Blair
Radia Jamil
Erin Hughes
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Navid Mahabadi
Hussain Sajjad
Steve Bhimji
Muhammad Hashmi
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beenish Sohail
Hajira Basit
Phillip Hynes
Sandeep Sekhon


Updated:
9/20/2019 3:32:27 PM

Introduction

Middle lobe syndrome (MLS) is a relatively uncommon clinical entity that is under-recognized in clinical practice. It was first identified clinically in 1948 by Graham et al. in a case series involving 12 patients with nontuberculous middle lobe atelectasis secondary to extensive compression by enlarged lymph nodes.[1] Recurrent or fixed right middle lobe opacification is almost pathognomonic for MLS; however, lingular involvement is common due to similar anatomic and physiological burdens. Though there has been no established definition of middle lobe syndrome, it has been recognized to involve two fundamentally different pathophysiological pathways that lead to recurrent middle lobe atelectasis: obstructive and nonobstructive.[2]

Etiology

The obstructive type of middle lobe syndrome usually results from extrinsic compression of the right middle lobe bronchus resulting from peribronchial lymphadenopathy or tumors that exploit the anatomic peculiarities of the right middle lobe bronchus[3]. It can classify into two subtypes: intraluminal or extraluminal obstruction.

Extrinsic compression may involve a plethora of tumors, including hamartomas, primary lung cancers, and distant metastasis from unknown primaries.[3][4] The most common etiology of the obstructive type is often subject to mediation by peribronchial lymphadenopathy secondary to granulomatous diseases, endemic fungal infections, and various mycobacterial species.[4][5][6][7][8] Other more exotic etiologies that cause an intraluminal obstruction, described in previous literature as isolated case reports, include sarcoidosis, aspiration, mucus plugs, and broncholiths.[9]

In the nonobstructive type, there is no identifiable obstruction on bronchoscopic evaluation, and the physiological basis of the recurrent atelectasis is poorly understood. The collateral ventilation of the middle lobe constitutes a zone of high resistance in comparison to the upper lobes, as a result of the higher ratio of pleural to the non-pleural surface area. The hypothesis is that ineffective collateral ventilation may play a significant role in the pathophysiology of middle lobe syndrome. Nonobstructive middle lobe syndrome is usually due to transient hypoventilation in the setting of chronic inflammatory and infectious changes (in conditions like cystic fibrosis) due to a wide array of infections, pulmonary infarcts, bronchopulmonary cysts, or disease processes that predispose to bronchiectasis.[10][9]

Epidemiology

Epidemiological data on middle lobe syndrome is very limited. There have been scattered case series and nationwide studies demonstrating a higher female to male ratio with women presenting later in age than their male counterparts.[9][11] Additionally, the poorly understood nonobstructive variant of middle lobe syndrome due to chronic inflammation is the most common etiology, accounting for over 60% of known cases.[3]

Pathophysiology

The pathophysiology of middle lobe syndrome varies by type. In obstructive middle lobe syndrome, there is a noticeable decrease in endoluminal diameter in the right middle lobe bronchus or left lingular bronchus due to extraluminal or intraluminal obstruction. The right middle lobe bronchus, in particular, is susceptible to near or total obstruction due to a smaller intraluminal diameter than other lobar bronchi.[12] Similarly, female patients have globally smaller intraluminal diameters compared to their male counterparts, thus providing anatomical evidence for a female predisposition epidemiologically.[12] Furthermore, the fissures of the middle lobe and lingula insulate these segments from collateral ventilation, thus reducing the likelihood of auto-correction of atelectasis and decreasing mucus clearance.[13][14]

History and Physical

A keen sense of awareness towards certain distinguishing features in the history and physical examination can raise the index of suspicion for diagnosis. The patients with middle lobe syndrome usually present with a constellation of symptoms such as chronic cough, hemoptysis, dyspnea, and features consistent with recurrent pneumonia. However, the most important aspect of history is an intrusive, recurrent, difficult to treat pneumonia. Physical exam findings would include wheezing, rhonchi, decreased breath sounds, tachypnea, and possibly diaphoresis during periods of concomitant pneumonia. In rare cases, features such as failure to thrive or cachexia may present as well, depending on the underlying etiology responsible for middle lobe syndrome.

Evaluation

There is a myriad of tests and imaging modalities available to assist in the diagnosis of middle lobe syndrome; however, none is satisfactorily sensitive or specific enough to be considered the gold standard for diagnosis. Initial evaluation with a PA and lateral chest X-ray would seem appropriate; however, these plain films may be normal in patients who have intermittent obstructions or recurrent pneumonia.[2] The classic silhouette sign with the right heart border obscured by a right middle lobe infiltrate may be present in AP or PA projections.[13] Nevertheless, a radiographic evaluation may best focus on identifying the underlying cause of the condition. Bronchoscopy, complete blood count, and/or CT chest may further help elucidate the underlying disease process responsible for the syndrome. 

Treatment / Management

Treatment for middle lobe syndrome, whether it is obstructive or non-obstructive, is directed at diagnosing and treating the underlying disease process. Agents directed towards optimizing pulmonary function (mucolytics, chest physiotherapy, bronchodilators, and antibiotics) are cornerstones of treatment and would most likely benefit all types of middle lobe syndrome irrespective of underlying etiology[15] Targeted antibiotic therapy towards Pseudomonas species is a strong recommendation, as the underlying structural changes associated with middle lobe syndrome enable it to be a viable medium for pseudomonal infections.

In obstructive type middle lobe syndrome, fiberoptic or rigid bronchoscopy would help remove foreign bodies or evaluate intrabronchial tumors. Clinicians have occasionally used insufflation with fiberoptic bronchoscopy for lobar collapse. However, there is no robust data regarding this approach, and it should only receive consideration on a case by case basis.[16][17] Ultimately, surgical intervention may play an essential role, if conservative and bronchoscopic management fails to produce favorable results. One study demonstrated that one-third of patients were successfully treated with conservative management, while one-third of patients went on to undergo surgical intervention.[18] The role of surgical intervention and possible lobectomy is only limited to obstructive MLS and data is limited to sporadic case reports in children. 

Differential Diagnosis

Differentials include, but are not limited to cystic fibrosis, bronchiectasis, aspergillosis, pulmonary sequestration, tuberculosis infection, asthma, chronic obstructive pulmonary disease, immunodeficiency, ciliary disorders, and other rare causes. 

Enhancing Healthcare Team Outcomes

Enhancing healthcare outcomes in middle lobe syndrome should primarily focus on the accurate detection of this condition. Pulmonologists should be actively involved in the management of patients with recurrent pneumonia or clinical suspicion of endobronchial obstruction, as their expertise with bronchoscopy may prove invaluable in the diagnosis and treatment of the underlying etiology. Patient education concerning pulmonary rehabilitation and chest physiotherapy may decrease the number of exacerbations.

Antibiotic stewardship is of particular importance in these patients as they often have infections with multi-drug resistant organisms that are difficult to treat; therefore, a pharmaceutical consult can be extremely helpful in this regard. Rapid de-escalation with appropriate cultures would be beneficial as it decreases the likelihood of subsequent multi-drug resistant infections. Coordination of pharmaceutical care with clinicians and pharmacists will result in better outcomes. 

Nursing can provide patient counseling, monitor treatment progress, and report to the treating clinician any concerns. Nursing can also verify patient compliance with treatment, both drug and other therapies. Age-appropriate vaccinations and limiting exposure to caustic chemicals or smoking can help prevent this condition. This type of interprofessional team coordination is crucial to the successful treatment of middle lobe syndrome. [Level V]


  • Image 11502 Not availableImage 11502 Not available
    Image courtesy O. Chaigasame
Attributed To: Image courtesy O. Chaigasame

Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Right Middle Lobe Syndrome - Questions

Take a quiz of the questions on this article.

Take Quiz
A 46-year old male patient presents to your clinic with recurrent pneumonia. Vital signs are as follows: Heart Rate 96 bpm, Blood Pressure 140/90 mmHg, Respiratory Rate 22, and SpO2 89%. Several chest x-rays in the past have demonstrated an infiltrate silhouetting with the right heart border. The patient denies any choking or any instances of aspiration. The segment of lung involved is anatomically similar to which of the following?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 56-year-old female presents to the emergency department with recurrent pneumonia. She has a chronic cough that now is productive with greenish sputum. Her vital signs include a blood pressure of 127/86 mmHg, temperature 99.8 F, heart rate 98 bpm, and SpO2 91%. A high-resolution CT demonstrates bronchiectasis involving the right middle lobe. She was most recently treated with a 7-day course of cefepime three weeks ago. Which of the following antibiotics would be the most appropriate empiric coverage?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 47-year-old female presents to the emergency department with chronic cough associated with hemoptysis. Physical examination reveals localized rhonchi and rales in the mid-lung fields. An extensive workup (including tuberculosis, aspergillosis, HIV, rheumatological, and inherited genetic disorders) is negative. The patient is found to have lobar infiltrate in the right middle lobe on the chest x-ray. A bronchoscopic evaluation would help differentiate between what subtypes of the underlying syndrome?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 46-year-old African American female presents to the emergency department with fevers, chills, and cough that has been ongoing for a week. At home, she had taken her mother's inhaler and some acetaminophen, however, her shortness of breath has persisted. She has had four similar episodes to this in the past two years. She is a former smoker and has recently traveled to Canada. She used to work at the local dry cleaner as a cashier. She intermittently experiences joint pain and lower extremity edema. Vital signs are normal except for a SpO2 of 91%. The initial x-ray reveals a consolidation obscuring the left heart border with bilateral hilar fullness and enlargement. Which of the following increases the likelihood of her most likely diagnosis?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 65-year-old female presents to the office as a new patient. She brings a handful of her previous x-rays which at times demonstrated infiltrates that silhouette with the right heart border. She reports she has had several instances of pneumonia but forgot her diagnosis. She has had extensive workup for tuberculosis, aspergillosis, cystic fibrosis and immunodeficiencies which have all been negative. What is the most common etiology of her diagnosis?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up

Right Middle Lobe Syndrome - References

References

GRAHAM EA,BURFORD TH,MAYER JH, Middle lobe syndrome. Postgraduate medicine. 1948 Jul;     [PubMed]
Gudbjartsson T,Gudmundsson G, Middle lobe syndrome: a review of clinicopathological features, diagnosis and treatment. Respiration; international review of thoracic diseases. 2012;     [PubMed]
Wagner RB,Johnston MR, Middle lobe syndrome. The Annals of thoracic surgery. 1983 Jun;     [PubMed]
Bertelsen S,Struve-Christensen E,Aasted A,Sparup J, Isolated middle lobe atelectasis: aetiology, pathogenesis, and treatment of the so-called middle lobe syndrome. Thorax. 1980 Jun;     [PubMed]
Bradham RR,Sealy WC,Young WG Jr, Chronic middle lobe infection. Factors responsible for its development. The Annals of thoracic surgery. 1966 Jul     [PubMed]
Kim HC,Kim HS,Lee SJ,Jeong YY,Jeon KN,Lee JD,Hwang YS, Endobronchial tuberculosis presenting as right middle lobe syndrome: clinical characteristics and bronchoscopic findings in 22 cases. Yonsei medical journal. 2008 Aug 30     [PubMed]
Kinzy JD,Powers WP,Baddour LM, Case report: Blastomyces dermatitidis as a cause of middle lobe syndrome. The American journal of the medical sciences. 1996 Oct     [PubMed]
Lambert GW,Baddour LM, Right middle lobe syndrome caused by Mycobacterium fortuitum in a patient with human immunodeficiency virus infection. Southern medical journal. 1992 Jul     [PubMed]
Kwon KY,Myers JL,Swensen SJ,Colby TV, Middle lobe syndrome: a clinicopathological study of 21 patients. Human pathology. 1995 Mar     [PubMed]
Rua J,Marques R,Silva R,Gomes B,Fortuna J, Non-Obstructive Middle Lobe Syndrome: An Unusual Cause of Recurrent Pneumonia in an Elderly Woman. European journal of case reports in internal medicine. 2018     [PubMed]
Mi W,Zhang C,Wang H,Cao J,Li C,Yang L,Guo F,Wang X,Yang T, Measurement and analysis of the tracheobronchial tree in Chinese population using computed tomography. PloS one. 2015;     [PubMed]
McElvein RB,Mayo P, Middle lobe disease. Southern medical journal. 1967 Oct;     [PubMed]
Illamperuma C,Reid J,Kanthan R, Chyloptysis with right middle lobe syndrome complicated postoperatively by chylothorax: an unusual cause of right middle lobe syndrome. Canadian respiratory journal. 2009 Mar-Apr;     [PubMed]
Einarsson JT,Einarsson JG,Isaksson H,Gudbjartsson T,Gudmundsson G, Middle lobe syndrome: a nationwide study on clinicopathological features and surgical treatment. The clinical respiratory journal. 2009 Apr     [PubMed]
Priftis KN,Mermiri D,Papadopoulou A,Anthracopoulos MB,Vaos G,Nicolaidou P, The role of timely intervention in middle lobe syndrome in children. Chest. 2005 Oct     [PubMed]
Paşaoğlu I,Doğan R,Demircin M,Hatipoğlu A,Bozer AY, Bronchoscopic removal of foreign bodies in children: retrospective analysis of 822 cases. The Thoracic and cardiovascular surgeon. 1991 Apr     [PubMed]
Wohlauer MV,Moore EE,Haenel JB,Burlew CC,Barnett CC Jr, Selective Intrabronchial Air Insufflation for Acute Lobar Collapse in the Surgical Intensive Care Unit. Journal of surgical radiology. 2011 Apr 1     [PubMed]
Livingston GL,Holinger LD,Luck SR, Right middle lobe syndrome in children. International journal of pediatric otorhinolaryngology. 1987 Jun     [PubMed]

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Rheumatology. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Rheumatology, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Rheumatology, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Rheumatology. When it is time for the Rheumatology board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Rheumatology.