Histologic Features

This section from the edge of a nodule shows tumor growing into an alveolar space.

Hyperplastic type II cells still line the alveolus, and are seen best at the right and top (arrowhead marks one). Compare the size of these cells and nuclei to that of the tumor cells in the alveolar nest (between arrows). Tumor cells here, in contrast to the compressed ones centrally, are large and have abundant pink cytoplasm. Sometimes the boundaries are poorly-defined. Nuclei are larger than those of the type II cells. They are rounded or lobulated and have peripherally clumped chromatin and a small nucleolus. One mitosis was found in 50 high power fields, a very low rate.

Clinical summary Image 3

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