A 38 year old male has paroxysmal hypeension. He is subsequently found to have medullary carcinoma of the thyroid, pheochromocytoma, and mucosal neuromas. Parathyroid involvement is not noted. What is the most likely diagnosis?

MEN III, also known as MEN IIb, is characterized by medullary thyroid carcinoma, pheochromocytoma, and mucosal neuromas.Wermer's syndrome is also called MEN type I . It is characterized by pancreatic (insulinoma), pituitary, and parathyroid involvement.Sipple's syndrome, or MEN type II , is similar to MEN III, but it has parathyroid involvement (tumor or adenoma) as opposed to neuromas. Ref: Wyatt C., Butterwoh IV J.F., Moos P.J., Mackey D.C., Brown T.G. (2008). Chapter 18. Endocrine Pathology. In C. Wyatt, J.F. Butterwoh IV, P.J. Moos, D.C. Mackey, T.G. Brown (Eds), Pathology: The Big Picture.