The ground glass changes are a combination of the cellular and exudative inflammatory response in the small airways, alveoli, interalveolar septa and interstitium, and thickened alveolar septum
The diagram shows the abnormal secondary lobule (a) The involved components include the small airways(b) alveoli and interalveolar interstitium (c) and the thickened interlobular septum (d) surrounding the secondary lobule due to an inflammatory process, cellular infiltrate and congestion of the venules and lymphatics in the septum. An anatomic specimen of a secondary lobule from a patient with thickened interlobular septa and interstitial thickening is shown in image e, and is overlaid in red (f) . A magnified view of an axial CT of the lungs in a patient with acute eosinophillic pneumonia shows thickened interlobular septa and centrilobular nodules (g) The inflammatory changes in the aforementioned structures result in an overall increase in density of the lung manifesting as ground glass changes (g) and overlaid in red (h)
Ashley Davidoff MD The CommonVein.net lungs-0762
This diagram reveals the important structural changes in the secondary lobule that includes filling of the alveoli with eosinophils and proteinaceous and fibrinous exudate as well as infiltration into the alveoar septa and interstitium (redwalls) . An important component of the disease is the thickening of the interlobular septa (maroon) which results in Kerley B lines and an interstitial pattern reminiscent of cardiogenic interstitial edema.
Ashley Davidoff TheCommonVein.net lungs-0758
Ashley Davidoff TheCommonVein.net
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Ground Glass Opacity (GGO) Caused by Cellular Accumulation with Partial Filling of the Alveolus Ground glass opacification may be caused by partial filling of the alveolus with cellular material with partial replacement of air with solid material with the net density being gray rather than white if the alveolus were fully filled. The black of the airway nor the white of the vessels may blend with the gray density and hence they are not visualized in ground glass opacities.
Ashley Davidoff MD TheCommonVein.net lungs-0707a
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