Fig. 1

Patient 1. Chest CT, lung window, axial plane; histological examination. a Baseline study. Nodules in the left lung, the larger lesion located in segment 1 + 2 of the upper lobe (black asterisk). The subsequent examination after one year (b) shows partial regression of lesions. Another chest CT during the follow -up (c) revealed a new nodule in the right upper lobe which enlarged at 3-month observation (black arrow) (d). e Microscopic image of poorly-differentiated squamous cell carcinoma in resection specimen (A—hematoxylin and eosin stain, magnification × 200; B—cytokeratin AE1AE3 immunohistochemical reaction, magnification × 200)