IdiopathicGiantCellGranulomatous Hypophysitis with Hypopituitarism, RightAbducens Nerve Paresis and MaskedDiabetes Insipidus

A38-year-old man presented withheadache, fever,and double visionassociated withrightabducens nerve paresis. He hadneither nuchal rigiditynorvisualfielddefect. Laboratory datarevealed elevated erythrocyte sedimentationrate(ESR), eosinophilia, andlymphocytic pleocytosis in thecerebrospinal fluid(CSF). Provocation testsof pituitaryhormones showed partialhypopituitarism. Magnetic resonance imaging (MRI) revealed swelling ofthehypophysis anda mass lesionexpanding intotherightcavernoussinus.Thesupplement doseof dexamethasone for hypothalamic hypocortisolism manifested diabetes insipidus. Biopsy, carriedoutthrough thetranssphenoidal approach, revealed giant cellgranuloma. Systemic granulomatous diseases were ruledout,andthelesionwas considered to beidiopathic giantcell granulomatous hypophysitis. Right abducens nerve paresis,diabetes insipidus anddysfunction of theanteriorlobewere amended bythetreatment with prednisolone for4 months, andfindings of thepituitary gland andstalkwere normalized. Thepresentcaseshows thatglucocorticoid hasaneffectonamendment ofidiopathic giant cellgranulomatous hypophysitis. (InternalMedicine 40:915-919, 2001)