Correct!
1. The thoracic CT shows numerous, bilateral, thin-walled pulmonary cysts

The thoracic CT shows numerous, thin-walled, bilateral, randomly distributed pulmonary cysts (Figure 4).

Figure 4. Axial unenhanced thoracic CT shows numerous, bilateral, randomly distributed thin-walled pulmonary cysts (arrowheads), some of which are subpleural (arrowheads in B, D, E), others of which are more centrally located. A linear focus with hyperattenuation, consistent with pleurodesis, is present in the right anterior thorax inferiorly.

Central thromboembolic disease is not evident, but would be exceedingly difficult to demonstrate on unenhanced thoracic CT displayed only in lung windows. No lung nodules are present; there is no evidence of miliary disease. Aside from the pulmonary cysts, the pulmonary parenchymal attenuation appears relatively homogeneous. The visible hilar and mediastinal contours appear normal; no evidence of lymph node enlargement is seen.

Which of the following represents the most likely cause for this patient’s spontaneous pneumothorax? (Click on the correct answer to proceed to the fifth of eight panels)

  1. The absence of lung nodules is atypical for TSC-LAM
  2. The appearance of the skin lesions is atypical for the angiofibromas / angioleiomyomata of TSC-LAM
  3. The lung cyst distribution is atypical for TSC-LAM
  4. The lung cyst morphology is atypical for TSC-LAM
  5. 1 and 2

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