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What is Neuroendocrine lesions of the lung are - and explain in detail?
The normal lung contains neuroendocrine cells within the epithelium as single cells or as clusters, the neuroepithelial bodies.
Neuroendocrine lesions of the lung may be of following types -

A. Non-Neoplastic
(i) Reactive neuroendocrine cell hyperplasia in response to inflammation or scarring.
(ii) Idiopathic pulmonary neuroendocrine cell hyperplasia → a precursor lesion of tumorlets and carcinoids.

B. Neoplastic
(a) Benign
(i) Tumorlets → Small, inconsequential hyperplastic neuroendocrine cells seen in areas of scarring or chronic inflammation.

(b) Malignant
(i) Carcinoid tumor
(ii) Small cell carcinoma of the lung
(iii) Large cell neuroendocrine carcinoma of the lung.