Neuroendocrine tumors represent 25% of primary lung neoplasms, of which only 2% are typical carcinoid. 75% of lung carcinoids originate from Kulchitsky cells in bronchus. Typical carcinoid tumors are well differentiated with low grade malignancy. Strong and diffuse positivity for neuroendocrine markers CD 56, synaptophysin and chromogranin is exhibited by these tumor cells. Carcinoid tumors in the past were excluded from TNM staging but 7 th edition of TNM staging system includes carcinoid.
The patients are usually younger than for usual lung cancers. Carcinoid syndrome is usually absent when the tumor is confined to lung. Markedly different prognosis and treatment underlies the importance of accurate pathologic diagnosis of neuroendocrine tumors of lung. Typical carcinoid has a five year survival up to 95% when there is complete surgical excision.
