Inflammatory Myofibroblastic Tumor of Lung

The alveolar architecture is largely intact in early stages of inflammatory pseudotumor. In later stages, the native lung architecture is completely effaced by collagen deposition. This image shows a trapped bronchiole (lower left) and a couple of alveolar airspaces (top), demonstrating the locally destructive nature of this lesion. Abundant plasmacytic infiltrate, characteristic of this lesion, can be appreciated in this field.