Definition
- Recurrent or persistent right middle lobe (or less commonly, lingular) atelectasis
Etiology
- Allergic Bronchopulmonary Aspergillosis (ABPA) (see Allergic Bronchopulmonary Aspergillosis)
- Asthma (see Asthma): predominantly seen pediatric cases with history of asthma or atopy
- Haemophilus Influenzae (see Haemophilus Influenzae): pediatric cases
- Granulomatous Mediastinitis and Fibrosing Mediastinitis (see Granulomatous Mediastinitis and Fibrosing Mediastinitis)
- Granulomatous Mediastinitis
- Blastomycosis (see Blastomycosis)
- Histoplasmosis (see Histoplasmosis): most common cause in the US
- Sarcoidosis (see Sarcoidosis)
- Tuberculosis (see Tuberculosis): common cause in the US
- Fibrosing Mediastinitis
- Blastomycosis (see Blastomycosis)
- Familial Multifocal Fibrosclerosis
- Histoplasmosis (see Histoplasmosis)
- Hodgkin’s Disease (Nodular Sclerosing) (see Hodgkin’s Disease)
- Methysergide (see Methysergide)
- Paraffin: previously used for plombage to treat tuberculosis
- Radiation Therapy
- Sarcoidosis (see Sarcoidosis)
- Silicosis (see Silicosis)
- Traumatic Mediastinal Hematoma
- Tuberculosis (see Tuberculosis)
- Granulomatous Mediastinitis
- Mycobacterium Avium-Intracellulare (MAI) (see Mycobacterium Avium-Intracellulare)
- Mycobacterium Fortuitum (see Mycobacterium Fortuitum)
- Sjogren’s Syndrome (see Sjogren’s Syndrome): lymphocytic bronchiolitis in the atelectatic lobes
- Streptococcus Pneumoniae (see Streptococcus Pneumoniae): pediatric cases
- Tumor: with extrinsic compression or intrinsic obstruction if right middle lobe bronchus
Physiology
- Mechanism
- Extrinsic compression (by surrounding lymph nodes) or right middle lobe bronchus
- Intrinsic obstruction of the right middle lobe bronchus
- Defects in right middle lobe bronchial anatomy (which characteristically has a “fish mouth” appearance, even in the normal state), inflammatory processes which cause surrounding lymphadenopathy, or abnormal collateral ventilation may be contributory factors
Clinical
- Right Middle Lobe Atelectasis: may be incidentally noted on CXR or Chest CT
- Cough (see Cough)
Treatment
- Early intervention (especially in children) may help to avoid chronic atelectasis or the development of bronchiectasis
References
- Allergic bronchopulmonary aspergillosis with middle lobe syndrome and allergic Aspergillus sinusitis. Eur Respir J. 1993 Jun;6(6):917-8 [MEDLINE]