Histologic changes: The pink scar (S) probably marks the residue of the ischemic necrosis just seen in the acute and organizing stages. There is no evidence that emphysema is a result of the wall necrosis. Sickle RBCs distend capillaries and arterioles or venules. The scattered cells in the alveolar spaces are mostly PMNs, but the ones with visible cytoplasm are macrophages. Alveolar edema is represented by the pale haze. It is likely that the alveolar PMNs are a manifestation of ischemia rather than infection in this case because pneumonia was not considered to be present clinically, and no organisms were seen on a Gram stain.

A

 

B. The subpleural scars and indentations noted in the slice of lung correspond to small, healed infarcts that cause contracture of the parenchyma and draw the pleura inward (arrow).

Clinical summary Image 6

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