This post is an answer to the Case – 52-year-old Man With History of Dyspnea
Findings
- The chest radiograph show lower-lobe-predominant emphysema with increased lung volumes.
- Thin-section CT confirms the radiographic findings, with increased lucency affecting the entire secondary pulmonary lobule. The process is more severe in the bases and is associated with lower lobe bronchiectasis and scarring.
Differential Diagnosis
The differential comprises pan-lobular (pan-acinar) emphysema, centrilobular emphysema, and bronchiolitis obliterans.
Teaching Points
- Pan-lobular/pan-acinar emphysema affects the entire secondary lobule uniformly. It can be differentiated from centrilobular emphysema by the lack of visualization of the central arteriole and bronchiole on HRCT.
- Pan-lobular emphysema tends to be more severe in the lower lobes. This distribution has been postulated to be related to the increased blood flow and increased number of neutrophils and macrophages (the source of the alpha-1 antiprotease) in the bases.
- When mild, pan-acinar emphysema can be hard to separate from bronchiolitis obliterans and other small airways diseases.
- Similar pathologic findings can be seen in the emphysema associated with excessive intravenous drug use, most notably methylphenidate (Ritalin).
- Alpha-1 antitrypsin deficiency is also associated with bronchial wall thickening and bronchiectasis.
- The lung destruction in this condition can be accelerated by cigarette use.
- Lower-lobe-predominant emphysema should prompt one to consider alpha-1 antitrypsin deficiency or intravenous drug abuse (most notably Ritalin).
- Ventilation-perfusion scintigraphy typically shows increased retention of xenon and decreased perfusion in the lower lobes bilaterally.
Management
- Most patients are mildly symptomatic in the early stages of the disease.
- Clinical symptoms will guide the clinician more than imaging. When the disease is severe, patients may require lung transplantation.
READ MORE: COPD (Emphysema and Chronic Bronchitis): From Diagnosis to Treatment
SIMILAR CASES:
Further Reading
Newell JD Jr. CT of emphysema. Radiol Clin North Am. 2002 Jan;40(1):31-42, vii. doi: 10.1016/s0033-8389(03)00107-6. PMID: 11813818.
