389- What is multiple endocrine neoplasia type 2 syndrome?
Multiple endocrine neoplasia type 2 (MEN2) syndrome is an autosomal domi-
nant inherited disorder characterized by multiple endocrine organ involvement
of neural crest origin. Classically, the MEN2 syndrome is subdivided into
MEN2A and MEN2B, and with the current classification, familial medullary
thyroid carcinoma is also considered as part of MEN2 syndrome.- What are the components of MEN2A syndrome?
MEN2A syndrome consists of medullary thyroid carcinoma, pheochromocy-
toma, and PHPT. Medullary thyroid carcinoma (MTC) is usually present in
almost all patients (100 %), whereas pheochromocytoma is present in 30–50 %
and PHPT in 10–20 % of patients with MEN2A syndrome. The dermatological
manifestation of MEN2A syndrome is cutaneous lichen amyloidosis which
usually occurs in 30 % of patients and is invariably associated with codon 634
mutations of RET proto-oncogene. It is a precocious marker of future develop-
ment of MTC. In addition, Hirschsprung disease (7 %) is also associated with
MEN2A syndrome (Fig. 11.3).a bFig. 11.3 (a) A patient with MEN 2A syndrome with a scar in the neck. (b) Note the cutaneous
lichen amyloidosis over the nape of the neck in the same patient
11 Multiple Endocrine Neoplasia