Pulmonary neuroendocrine tumours and proliferations: a review and update

Pulmonary neuroendocrine tumours include the low-grade typical carcinoid, the intermediate-grade atypical carcinoid, and the high-grade large cell neuroendocrine and small cell carcinomas. This group of tumours continues to be the subject of much investigation. Continuing issues include the examination of the relationship of these tumours to each other from a molecular standpoint, the appropriate criteria for classification, choice of nomenclature and whether or not the two high-grade carcinomas warrant separate classification. Additionally, diffuse idiopathic neuroendocrine cell hyperplasia and carcinoid tumourlets are being recognized with greater frequency.