It has been observed that endocrine neoplasias, such as pheochromocytoma [31], medullary thyroid carcinoma [32], carcinoid [33], insulin-producing pancreatic tumor [34], and small cell lung carcinoma (SCLC) [35, 36] may differentiate into neural cells in vitro. This evidence concerns the gene INS and hereditary pheochromocytoma-paraganglioma.