Radiographic findings:

A plain film taken on admission (5/19) showed a small right effusion and hazy right mid and lower chest density. The left lung appeared normal.

What structures that identify the density as pulmonary consolidation can faintly be seen in the right lower chest ?

Which lobe is consolidated, and how do you know?

Answer 1

CT on 5/25 confirms the RLL consolidation (note some sparing of the anterior RLL) and nicely demonstrates aerated bronchi in the consolidation. The left lung shows an irregular nodule with ill-defined margins, and patchy opacities are seen in the LLL.

For pathologic correlation see Discussion--Table 1.

CT at the level of the upper lobes shows extensive ground-glass opacity, bilaterally.

How is ground-glass opacity different from consolidation on CT?

What is the differential diagnosis for ground-glass density?

Answer 2

Clinical summaryImage 1

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Answer 1

 

What structures that identify the density as pulmonary consolidation can faintly be seen in the right lower chest ?

Answer: Bronchi outlined by consolidated lung seen as "air-bronchograms."

Which lobe is consolidated, and how do you know?

Answer: RLL. The right heart border (an anterior structure) is clearly defined, but would be obscured with RML consolidation (RML is anterior). Portions of the diaphragm (inferior structure) are obscured which occurs with RLL consolidation (RLL is inferior). The fact that portions of the diaphragm are well-defined is consistent with aeration of portions of the anterior basilar RLL.

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Answer 2

 

How is ground-glass opacity different from consolidation on CT.

Answer: Consolidation totally obscures vessels as in the RLL. The upper lobes show hazy density through which vessels can be clearly seen.

For pathologic correlation see Discussion--Table 1.

What is the differential diagnosis for ground-glass density? Answer: The differential diagnosis for ground-glass opacity is extensive and includes pulmonary edema and hemorrhage, interstitial pneumonias (UIP, DIP, LIP, and acute), hypersensitivity pneumonia, atypical infectious pneumonias such as Pneumocystis carinii, mycoplasma, or CMV pneumonia, and cryptogenic organizing pneumonia [1].

Comments on ground-glass opacity: In CT, particularly high-resolution CT (HRCT), the term "ground-glass" is used if hazy lung opacity does not obscure underlying blood vessels (as opposed to "consolidation" which obscures vessels) [2] . When pulmonary morphologic abnormalities below the resolution of HRCT (at best 0.1 to 0.2 mm [3]) are imaged, ground-glass opacity is produced as a result of volume averaging [2]. The presence of ground-glass opacity signifies minimal thickening of the alveolar walls or partial filling of the alveolar air spaces with fluid or cells. Also, small amounts of fluid lying against alveolar walls can give the same appearance as alveolar wall thickening [2]. Leung, et al. studied 22 patients with ground-glass opacity at HRCT. Histology showed primarily interstitial disease in just over 1/2, interstitial and air-space disease in 1/3, and predominantly air space disease in 1/7 [4].

References

1. Webb W, Müller N, Naidich D: High-resolution CT of the Lung, 2nd ed. Philadelphia, Lippincott-Raven Publishers, 1996, pp 75-78.

2. Webb W, Müller N, Naidich D: High-resolution CT of the Lung, 2nd ed. Philadelphia, Lippincott-Raven Publishers, 1996, pp 73-74.

3. Webb W, Müller N, Naidich D: ibid. p 13.

4. Leung A, Miller R, Müller N. Parenchymal opacification in chronic infiltrative lung diseases: CT-pathologic correlation. Radiology 1993;188:209-214.

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Clinical summaryImage 1

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