Pathology

• Intercellular bridges (desmosomes)

• Keratin pearls

• Glandular tumor

• Mucin-producing cells (positive mucin staining)

• Lepidic growth: noninvasive tumor growth at intact alveoli.

• Poorly differentiated, large polygonal tumor cells (abundant cytoplasm)

• Prominent nucleoli

Kulchitsky cells

• Small, dark blue neuroendocrine cells

• Hyperchromatic nuclei (salt and pepper appearance)