A “NET G3” subgroup often demonstrates an IHC pattern of chromogranin A positivity, EZH2 negativity, SSTR2A expression, and retained RB/TP53, contrasting with true LCNEC, which more frequently exhibits EZH2 overexpression, RB loss, and abnormal p53. Here, RB1 is linked to large cell neuroendocrine carcinoma.