Which of the following is false regarding medullary carcinoma of the thyroid?

The malignancy originates in the parafollicular &;C&; cells, which reside in the upper poles of the thyroid lobes and are of neural crest origin. MTC occurs most commonly in a sporadic form (80%); it occurs less commonly as an autosomal dominant inherited disorder such as MEN2A, MEN2B, and familial medullary thyroid carcinoma (FMTC).Excess secretion of calcitonin has been shown to be an effective marker for the presence of MTC, Carcinoembryonic antigen may also be elevated in MTC. This calcitonin excess is not clinically associated with hypocalcemia but may rarely result in symptoms of diarrhoea and flushing in patients with advanced disease.Amyloid infiltrate seenRef: Sabiston 20e, page no: 932