Fig. 4

Pathological analysis of the radical resection specimen. On gross examination, the tumor appears yellowish, firm, and solid (A). Low power magnification shows prominent endobronchial growth (B). Tumor cells are arranged as flaky nests and adenoid clusters in the matrix with hyaline degeneration (C). Nuclei are lightly atypical with a small blue nucleolus (D). Mucous secretion was observed in the gland-like space (E) and confirmed by alcian blue and periodic acid schiff staining (F)