Radiographic Findings

CT of the upper chest shows multiple right apical bullae in a subpleural distribution (consistent with paraseptal emphysema) and a small portion of the large right pneumothorax seen anterior to the bullae. The lungs are remarkable for diffuse ground-glass opacity.

The patient was admitted, and a right thoracostomy tube was placed.

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) [1]. When pulmonary morphologic abnormalities below the resolution of HRCT (at best 0.1 to 0.2 mm [2]) are imaged, ground-glass opacity is produced as a result of volume averaging [1]. 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 [1,3]. Leung, et al. studied 22 patients with ground-glass opacity at HRCT, and at histology found primarily interstitial disease in just over 1/2, interstitial and air-space disease in 1/3, and 1/7 with predominantly air space disease [4].

The differential diagnosis for ground-glass opacity includes pulmonary edema and hemorrhage, interstitial pneumonias (UIP, DIP, LIP, and acute), hypersensitivity pneumonia, atypical infectious pneumonias such as Pneumocystis carinii or CMV pneumonia, and cryptogenic organizing pneumonia [5]. (See continuation below.)


1. Webb WR, Müller NL, Naidich DP: High-resolution CT of the Lung, 2nd ed. Philadelphia, Lippincott-Raven Publishers, 1996, pp 73-74.

2. Webb WR, Müller NL, Naidich DP: ibid. p 13.

3. Naidich D, Zerhouni E, Hutchins G, Genieser N, McCauley D, Siegelman S. Computed tomography of the pulmonary parenchyma. Part 1: Distal air-space disease. J Thorac Imaging 1985; 1:39-53.

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

5. Webb WR, Müller NL, Naidich DP: High-resolution CT of the Lung, 2nd ed. Philadelphia, Lippincott-Raven Publishers, 1996, pp 75-78.

Clinical summary continued: The patient's respiratory status improved, but he had a persistent mild to moderate air leak. Bronchoscopy with BAL, performed on the first hospital day, was negative for pneumocystis. He eventually underwent talc pleurodesis on the right, and the thoracostomy tube was removed.

Over the course of the hospitalization, the patient's interstitial abnormalities progressed, and he developed worsening hypoxemia and recurrent fevers. He was placed on empiric therapy for pneumocystis, as well as coverage for typical and atypical bacterial pathogens.

A second bronchoscopy with transbronchial biopsy again revealed no organisms.

Transbronchial biopsy: The generous transbronchial biopsy shows diffuse, coagulative necrosis of all structures including alveolar walls (right upper quadrant) and a large vessel (arrow). What is the cause of this type of necrosis? Answer

Clinical summary Radiology

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Answer: Coagulative necrosis is usually caused by ischemia (infarction).