CARCINOID TUMOR OF THE LUNG
Represents 1-5% of the lung tumors.
Most tumors have excellent prognosis and can be treated by surgical removal. About 90% of the tumors are aggressive and show the potential of local invasion or distant metastasis.
Grossly the tumor appears as a intrabronchial polypoid mass which measures about 3-4 cm. The tumor is highly vascular and may bleed.
Microscopically, the tumor is composed of nests of small, uniform, round cells. In some instances, the tumor cells exhibit atypia, pelomorphism and mitotic figures. Presence of the neurosecretory granules can be demonstrated at the ultrastructural level or by immunostaining for chromogranin, neuron specific enolase, calcitonin, and bombesin.