Fig. 3

A: In the right lower lobe, a jelly-like lesion measuring 5.5 cm in maximum diameter was observed, with a central nodule measuring 0.7 × 0.5 × 0.3 cm. B: The tumor exhibited papillary growth and displayed a vascular axis when examined at low power view (H-E×4). C: At high magnification (H-E×20), the papillae were lined with cuboidal or columnar epithelium characterized by basophilic cytoplasm, small nuclei with uniform chromatin, absence of obvious nucleoli, and lack of mitotic figures. D: Immunohistochemistry revealed a Ki-67 proliferation index of 2%