Figure 1
Histological appearance of the lung biopsy specimen. Malignant tumor cells were arranged in clusters and an acinar pattern, suggestive of adenocarcinoma. (A) Positive immunohistochemical staining for cytokeratin 20. (B) Positive immunohistochemical staining for caudal-related homeodomain transcription factor 2. (C) Negative immunohistochemical staining for cytokeratin 7. (D) Negative immunohistochemical staining for thyroid transcription factor-1.