In summary, the characteristics of thyroid lesions in CNC are as follows: (1) the thyroid lesions are present without major symptoms and are usually accompanied by other neoplastic syndromes in various organs, (2) adenomas are the predominant pathology of thyroid lesions, and they tend to increase in size and number during a long follow-up, (3) the age of onset of thyroid lesions is younger in cases with PRKAR1A genetic mutation, and (4) thyroid cancer develops in 6% of CNC patients, but they are well-differentiated cancers, i.e., papillary or follicular cancer, with favorable prognoses. The gene discussed is PRKAR1A; the disease is thyroid cancer.