AQP1 and congenital isolated adrenocorticotropic hormone deficiency: The particularity of this case report belongs to: first, the association of sialadenitis and isolated adrenocorticotropic hormone deficiency, which has never been described before; second, the use of an 11C-methionine positron emission tomography/magnetic resonance (methionine PET/MR) for exploring the metabolism of the pituitary gland; and finally the immunostaining of aquaporins 1, 3, and 5 for understanding the pathophysiology of sialadenitis in this situation.