Immunohistochemistry (IHC) for napsin A has been widely used to support a diagnosis of lung adenocarcinoma with reported high sensitivity (59% - 100%) [3-6], specificity (88 - 94%) [5,6], positive predictive value (78 - 90%) [5,6], and negative predictive value (72 - 96%) [5-7]. The gene discussed is NAPSA; the disease is lung adenocarcinoma.