RET and familial medullary thyroid carcinoma: MEN2A accounts for 95% of MEN2 syndromes with four identified variants: classical MEN2A (MTC sometimes associated with pheochromocytoma, or hyperparathyroidism, or both), MEN2A with cutaneous lichen amyloidosis, MEN2A with Hirschsprung’s disease, and familial MTC (MTC without pheochromocytoma or hyperparathyroidism) [6].