Idiopathic granulomatous hypophysitis is a chronic inflammation of the pituitary gland. It has a rare occurrence and is diagnosed only on pathologic examination. We report a case of a 60-year-old patient presenting with headache, vomiting and isolated hyponatremia. MRI study showed a space occupying lesion of the pituitary gland with a marked enhancement after gadolinium injection. Pituitary biopsy was consistent with the diagnosis of idiopathic granulomatous hypophysitis. The aim of this case report is to discuss the variable clinical and radiological aspect of the disease.