Xanthogranulomatous hypophysitis mimicking a pituitary neoplasm.

Hypophysitis is an inflammatory disease of the pituitary gland that clinically and radiologically mimics pituitary tumors. We report here a case of xanthogranulomatous hypophysitis mimicking a pituitary neoplasm.A 65-yr-old woman presented with weight loss, fatigue, and visual disturbance. Computed tomography demonstrated a round cystic low-density mass with calcification in the sella. A T1-weighted magnetic resonance imaging scan showed most of the mass as hyperintense. The capsule of the mass was strongly enhanced by gadolinium. Endocrinologic examination revealed hypocorticism and hypothyroidism. Diabetes insipidus (DI) developed after the administration of hydrocortisone. The patient also had hallucination and delusions of persecution. Transsphenoidal surgery was performed. Histologic examination of the removed tissue showed central necrosis surrounded by accumulation of foamy cells and epithelioid cells. Several multinucleated giant cells were also seen. The foamy cells and epithelioid cells were immunopositive for Kp-1, a marker of macrophages. The patient made an uneventful postoperative recovery. Although DI and hypofunction of adenohypophysis persisted, the visual disturbance and psychiatric disorder were resolved. We have described an unusual inflammatory lesion of the pituitary in the sellar region that was mimicking neoplasm. A high level of clinical suspicion of inflammatory disorders is necessary for correct diagnosis and optimal management.