For an accurate diagnosis, LCNEC requires the presence of neuroendocrine features identified using light microscopy, neuroendocrine differentiation confirmed by electron microscopy and/or immunohistochemistry (synaptophysin, chromogranin A or CD56 positivity), mitoses ≥11 per 2 mm2, and non-small cell cytomorphology with abundant eosinophilic cytoplasm and prominent nucleoli (30). The gene discussed is SYP; the disease is large cell neuroendocrine carcinoma.