Fig 3.

Cytology from the initial lung fine-needle aspirate. A, A smear from the lung fine-needle aspirate shows a population of cells larger than the adjacent neutrophils (white arrows). The nuclei have an open fine chromatin with one or two tiny pale blue nucleoli. Note the vacuoles in the blue cytoplasm (gray arrows). B, Sections from the cell block show a population of poorly cohesive cells with a diffuse fine nuclear chromatin, slight variation in nuclear size and outline, and no obvious nucleoli. The cytoplasm appears delicate, vacuolated, and disrupted (arrow).