Figure 4.

Picric acid-collagen staining of three PA cases of different texture. A. Soft texture PA under microscope. A large number of tumor cells (black), a small amount of fresh red collagen tissue (arrows) and rich cytoplasm (brown yellow) were seen. B. Medium texture PA under microscope. Moderate strip or bundle collagen fiber (red), tumor cells (black), and rich cytoplasm (brown yellow) was seen. C. Tough texture PA under microscope. A large number of collagen fibers (red), a small amount of tumor cells (black) and little cytoplasm (brown yellow) was seen.