Multiple endocrine neoplasia type 2B (MEN2B) is a form of MEN2 syndrome, characterized by a medullary thyroid carcinoma (MTC), pheochromocytoma, mucosal ganglioneuromas and arfanoid habit.
The exact prevalence is unknown but it is up to 5-10% of all MEN2 syndromes and is the most aggressive form of the disease. Transmission is autosomal dominant. It is associated only one mutation at codon 918 of the tyrosine kinase domain of the RET proto-gene subtype MEN2B.
His appearance occurs more frequently in young children. Unlike syndrome MEN2A, the hiperparotiroidismo is not present. Due to a ganglioneuromatosis the gastrointestinal tract, the early signs of the disease are usually: chronic constipation, bloating, diarrhea or megacolon birth. Patients also show developmental abnormalities such as mucosal neuromas of the lips and tongue, lips and lumps habit Marfanoid (with skeletal abnormalities and joint laxity).
MEN2B patients have a poor prognosis and a higher mortality rate than those with MEN2A.