Foxp3-positive lymphocytes were more abundant in NEC than in non-NEC components in 18 (54.5%) and 16 (48.5%) cases and PD-1/CD4 ratio was greater in NEC than in non-NEC components in 12 (36.4%) and 15 (45.5%) cases, respectively. Here, CD4 is linked to neuroendocrine carcinoma.