Apical Cap
Jud W. Gurney, MD, FACR
DIFFERENTIAL DIAGNOSIS
Common
Normal Process of Aging
Pancoast Tumor
Less Common
Radiation Fibrosis
Pleural Effusion (Supine Position)
Lipoma or Extrapleural Fat
Rare but Important
Aortic Transection
Aspergilloma
Pseudosequestration
ESSENTIAL INFORMATION
Helpful Clues for Common Diagnoses
Normal Process of Aging
Sharp, smooth, or undulating margin, usually < 5 mm thick, often symmetric
Incidence increases with age
40 years: 5%; 70 years: 50%
Incidence of right (22%) apical cap more common than left (17%) apical cap
Histology similar to pulmonary infarct
Age-related development probably due to chronic ischemia
Pathophysiology: Normal pulmonary artery pressure just sufficient to get blood to lung apex
Pancoast Tumor
Asymmetric apical cap with convex margin > 5 mm thickness
Adjacent bone destruction of ribs (33%)
Helpful Clues for Less Common Diagnoses
Radiation Fibrosis
For Hodgkin disease (mantle), breast cancer (supraclavicular nodes), head and neck cancers
Pleural Effusion (Supine Position)
Apex in supine position most dependent portion of hemithorax
Lipoma or Extrapleural Fat
Usually bilateral, enlarged body habitus, fat density at CT
Helpful Clues for Rare Diagnoses
Aortic Transection
Left apical cap due to extravasation of blood in extrapleural space from related mediastinal bleeding or rib fractures
Aspergilloma
Consider when new pleural thickening occurs adjacent to preexisting cavity, such as tuberculosis
Aspergilloma may not be radiographically evident
Pseudosequestration
Refers to transpleural systemic-pulmonary artery anastomoses
Most commonly seen with severe pulmonary artery stenosis
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