Given the rarity of this mutation in NSCLC and its frequency in undifferentiated and dedifferentiated melanoma, we preferred to exclude this case, although in our experience with > 85 undifferentiated melanomas, CK7 expression and association with lung adenocarcinoma is very unusual and has not been encountered [5, 6]. The gene discussed is KRT7; the disease is non-small cell lung carcinoma.