Heterogeneity of so-called neuroendocrine lung tumors.

The diagnosis of neuroendocrine (NE) lung tumor is dependent on a number of observations: organoid structure, dense core granules, and various molecular components, including chromogranin A, neurosecretory enolase, synaptophysin, neural cell adhesion molecules, and others. None of these is specific for lung tumors. The Kulchitsky cell, which has these characteristics, forms a carcinoid, which exemplifies the NE tumor. It is euploid, has few mitoses, no necrosis and a 5- to 10-year survival of over 90%. When carcinoids show malignant characteristics, i.e., increased mitoses and necrosis, they have been labeled atypical and have a survival of 50%. Because all other non-small cell lung tumors, especially large cell tumors, may show one or more of these things because of the inherent heterogeneity of lung tumors, the term NE has been applied to them without real evidence that this affects survival with or without chemotherapy. This is expensive and without clinical significance. Copyright 2001 Academic Press.