Neuroendocrine neoplasms of the lung: a pathology update

Purpose: Neuroendocrine tumors and neuroendocrine carcinomas in the lung are distinct and separate entities featuring neuroendocrine differentiation, for which an accurate classification is clinically warranted. Materials and methods: Three perspectives were addressed: (i) diagnostic tools, with the terminology to be used in either resection specimen or small-sized material; (ii) the so-called carcinoid tumors with elevated proliferation rates (mitotic and/or Ki-67 activity); (iii) predictive biomarkers based on immunohistochemical characterization. Results: We herein provide a pathology update on lung neuroendocrine neoplasm classification that will appear in the forthcoming 5th edition of the WHO Blue Book, including a short discussion about biomarkers, which are presently given full consideration in clinical practice. Conclusion: The WHO classification on lung neuroendocrine neoplasms is the cornerstone to provide the best clinical management of patients and is the starting point for any investigative insight.