Fig. 2.
Histopathological findings of the lung specimens. (a) Hematoxylin and eosin staining of the lung tissue obtained by bronchoscopic biopsy, showing histopathology of adenocarcinoma. (b) Immunohistochemical staining of thyroid transcription factor 1, demonstrating strong nuclear expression in tumor cells. (c) Post-afatinib, hematoxylin and eosin staining of lung tissue showed small cell lung cancer transformation. (d) Post-afatinib, immunohistochemical staining of lung tissue showed strong staining for CD56.