Histologic Changes

An open lung biopsy of the left upper lobe shows widening of alveolar walls by loose, granulation tissue in a bluish matrix. Type II cells are prominent, and scattered interstitial lymphoid cells are present. Eosinophils and PMNs are rare. The alveolar spaces contain increased numbers of macrophages.

The arrow points to hyaline membranes that were present focally. This pattern corresponds to ground-glass on the CT.

A higher magnification shows the interstitial, inflammatory cells (small, dark nuclei), granulation tissue (vesicular nuclei), and type II cells.

The collection at the arrow represents alveolar granulation tissue in the process of being epithelialized and incorporated into the interstitium. Note the type II cells at the arrow and their absence elsewhere around this collection.

Clinical summary Image 3

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