C-cell hyperplasia (CCH) and medullary thyroid carcinoma (MTC) in patients affected by germline mutations of the RET oncogene represent an exceptional opportunity to study the regulation of proliferation and apoptosis during tumour initiation and progression.
Among RET mutation-positive patients, thyroidectomy performed for clinical or biochemical indication disclosed medullary thyroid carcinoma in 44 (98%) of 45 patients and precursor C-cell hyperplasia in only 1 (2%) patient.
Recently, a somatic mutation at codon 918 of RET was reported in medullary thyroid carcinoma (MTC) and C-cell hyperplasia in patients with MEN 2A or familial MTC (FMTC), suggesting its possible contribution to tumorigenesis.
Histologic examination of the thyroid glands in the two RET mutation negative individuals who had thyroidectomy demonstrated C-cell hyperplasia in one but not in the other.
The noncarriers included seven persons who had previously undergone thyroidectomies for suspected C-cell hyperplasia but were negative for the RET mutation present in affected members of their families.