ALK and neoplasm: Immunohistochemically, the tumor cells, described above, were diffusely positive for cytokeratin 5 (clone XM26, Fig. 3a and b) and p40 (clone BC28, Fig. 3c), and were negative for cytokeratin 7 (clone OV-TL 12/30), thyroid transcription factor 1 (clone 8G7G3/1), Napsin A (polyclonal), desmin (clone D33), alpha-smooth muscle actin (clone 1A4), anaplastic lymphoma kinase (ALK, clone 5A4), and nuclear protein in testis (NUT, clone C52B1).