[A case of pituitary abscess caused by infection of Rathke's cleft cyst].

Pituitary abscess is relatively rare. Only about 80 cases have been reported. Preexisting lesions in pituitary fossa, such as pituitary adenoma, craniopharyngioma and Rathke's cleft cyst, are inclined to be complicated by infection more than the normal pituitary glands are. We reported a case of pituitary abscess caused by infection of Rathke's cleft cyst. A 67-year-old male had general fatigue and loss of appetite 4 months before admission. On admission he was found to have diabetes mellitus, diabetes insipidus, and hypernatremia. These defects were controlled by medication but he gradually became comatose and febrile. CT and MRI revealed an intrasellar lesion with ring enhancement. Lumbar puncture demonstrated an increase of mononuclear cells and protein. Blood chemistry revealed a marked increase of CRP. He was operated on via the transsphenoidal approach, which revealed sphenoid sinusitis and abscess formation in the pituitary gland. Histological examination of the surgical specimen revealed infection of Rathke's cleft cyst but the fluid in the cyst was sterile. By the drainage of the cyst and the use of antibiotics the patient became alert and signs of infection disappeared. He was discharged with a slight hypopituitarism and returned to normal life. Mortality rate of pituitary abscess is decreasing but is still high because of hypopituitarism and severe infection. Accurate diagnosis and operation are necessary. Transsphenoidal surgery is preferable for postoperative drainage of the abscess.