Multiple endocrine neoplasia type IIB (MEN2B) is a rare autosomal dominant cancer syndrome characterized by aggressive medullary thyroid carcinoma (MTC) (up to 100% of patients), pheochromocytoma (50%), mucosal neuromas (91%-96%), intestinal ganglioneuromatosis (40%-71%), and marfanoid habitus (65%-75%). Ninety-five percent of MEN2B patients have germline gain-of-function mutations of the rearranged during transfection (RET) proto-oncogene located on chromosome 10q11.2.

MEN2B usually presents in children. Mucosal neuromas are a very common finding appearing in children as young as 2 years. MTC typically develops in the first or second decade of life and may occur as early as the first year of life. MTC is marked by neck mass, lymphadenopathy, or diarrhea and flushing in advanced cases. An early history of nonspecific gastrointestinal complaints is common due to diffuse intestinal ganglioneuromas. The usual presentation of pheochromocytoma is in the second or third decade. Approximately 50% of patients will have multiple pheochromocytomas; these will often be bilateral.

Skeletal abnormalities of marfanoid body habitus are seen later in childhood. They include an elongated face and extremities, pronounced joint laxity, kyphoscoliosis, and pectus deformities.

Related topics: MEN1, MEN2a