A case of subarachnoid hemorrhage with pituitary apoplexy caused by idiopathic hypertrophic pachymeningitis.

Steroid therapy is considered to improve clinical symptoms in hypertrophic pachymeningitis. We present a 70-year-old man with idiopathic hypertrophic pachymeningitis, whose clinical signs progressively worsened despite steroid therapy. He died of subarachnoid hemorrhage (SAH) with pituitary apoplexy 2 months after the admission regardless of improvement of laboratory data and magnetic resonance imaging appearance by one-and-half-month steroid therapy. Autopsy revealed thickened dura mater supporting the diagnosis of hypertrophic pachymeningitis. Brain parenchyma is generally not affected by the disease; however, histological investigation suggested that inflammation of the dura caused damage to superior hypophyseal artery resulting in SAH and apoplexy in the anterior lobe of the pituitary gland. The higher dose and the longer duration of steroid therapy should have achieved in our case although most laboratory data recovered within the normal range. The aggressiveness of hypertrophic pachymeningitis must be evaluated by clinical signs rather than by laboratory data or imaging examinations.