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. 2022 Jul 30;22:293. doi: 10.1186/s12890-022-02090-z

Fig. 2.

Fig. 2

Evaluation of STAS. A, B Diagnosis of STAS by hematoxylin & eosin staining. STAS (arrowheads) was located within the normal alveolar lumen, outside the margin (black dashed line) of the main tumor. Further, STAS ≤ 3 alveolae away from the main tumor were classified as limited (A), STAS > 3 alveolae away from the main tumor were classified as limited extensive (B). C STAS was identified by immunohistochemistry. STAS (arrowheads, Napsin A positive) was located within the normal alveolar lumen, outside the margin (black dashed line) of the main tumor. STAS: tumor spread through air spaces