However, in contrast with previous observations, we observed that in a subset of TC, p16Ink4A display an aberrant pattern in a proportion of tumor cells (i. e. sporadic staining pattern in TCs and sporadic to focal staining pattern in ACs), suggesting that the immunohistochemical assessment of this tumor suppressor protein should be performed and interpreted carefully in the lung, recording every single positive cell. This evidence concerns the gene CDKN2A and neoplasm.