Right middle lobe syndrome is usually encountered in older adults, with a predilection for women (see Lady Windermere syndrome). It is also seen in children 1.
In most cases, patients are asymptomatic. Otherwise, a chronic cough is the most common symptom. Hemoptysis, chest pain, and dyspnea are also reported 1.
The underlying etiology of right middle lobe syndrome remains poorly understood, but poor collateral ventilation, a relatively narrow ostium, and infection/inflammation are all thought to play a role 3. The histological process identified in such cases include 1:
- chronic bronchitis or bronchiolitis
- lymphoid hyperplasia
- granulomatous inflammation
- Mycobacterium avium complex infection (classic but found only in a minority of cases)
- organizing pneumonia
The radiographic features of right middle lobe syndrome are a combination of:
Importantly, an obstructing bronchial lesion is usually not found.
- 1. Miller WT. Diagnostic thoracic imaging. McGraw-Hill Professional. (2006) ISBN:0071413006. Read it at Google Books - Find it at Amazon
- 2. Webb WR, Higgins CB. Thoracic Imaging, Pulmonary and Cardiovascular Radiology. Lippincott Williams & Wilkins. (2010) ISBN:1605479764. Read it at Google Books - Find it at Amazon
- 3. De boeck K, Willems T, Van gysel D et-al. Outcome after right middle lobe syndrome. Chest. 1995;108 (1): 150-2. doi:10.1378/chest.108.1.150 - Pubmed citation