What's on this Page
What is multiple endocrine neoplasia type 2b (MEN 2b)?
Multiple endocrine neoplasia type 2b (MEN 2b) an autosomal dominant inherited disorder, is characterized by multiple mucosal neuromas (conjunctiva, oral cavity, tongue, pharynx, and larynx), medullary thyroid carcinoma, pheochromocytoma, ganglioneuromatosis, bony deformities, marfanoid appearance, muscle underdevelopment, and hypotonia.
Gross and microscopic abnormalities of the peripheral autonomic nervous system affect both sympathetic and parasympathetic systems.
Patients have disorganized hypertrophy and proliferation of autonomic nerves and ganglia (ganglioneuromatosis).
Neural proliferation of the alimentary tract (Auerbach and Meissner’s plexi), upper respiratory tract, bladder, prostate, and skin also may be seen.
The clinical autonomic manifestations include impaired lacrimation, orthostatic hypotension, impaired reflex vasodilation of the skin, and parasympathetic denervation supersensitivity of pupils, with intact sweating and salivary gland function.
Nerve biopsy shows degeneration and regeneration of unmyelinated fibers.
A few point mutations in the RET proto-oncogene located on chromosome 10 have been associated with the disease.
Genetic testing is critical for detection of young carriers, who can undergo regular screening for medullary thyroid cancer.
Sources
Norcliffe-Kaufmann L, Kaufmann H: Familial dysautonomia (Riley-Day syndrome): when baroreceptor feedback fails. Auton Neurosci 172:26, 2012.
