Right Middle Lobe Syndrome (Brock Syndrome)

Definition

  • Recurrent or persistent right middle lobe (or less commonly, lingular) atelectasis

Etiology


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]