All are involved in MEN IIA except:
a. Pituitary(Ref: Nelson's 20/e p 2694-2481, Ghai 8/e p 523)In Multiple Endocrine Neoplasia (MEN) IIA, features seen are: "HAPPY", i.e. Hirschsprung disease, Amyloidosis, Pheochromocytoma, Parathyroid hyperplasia/Adenoma and thyroid Carcinoma (Medullary).
Pituitary
Parathyroid
Thyroid
Adrenal
Endocrinology