[Histopathological study of the "cholesterol granuloma reaction" in the sellar and juxta-sellar tumors].

Specimens from operation of 211 sellar and juxta-sellar tumors were observed histopathologically, and discussed about the true form of "cholesterol granuloma reaction" in those tumors. Depending on the characteristic histological feature, "cholesterol granuloma reaction" was classified into 3 groups, each of which also represented a step of process of organization. Group I (cholesterol clefts predominates in hemorrhagic and necrotic foci), group II (foreign body giant cells, macrophages, round cell infiltrations are present other than cholesterol clefts, signifying active organization), group III (numerous cholesterol clefts predominates in fibrous scar tissue). Feature of "cholesterol granuloma reaction" were seen in 6 cases among 37 cases of craniopharyngioma with verified histology (16%), 8 among 165 in pituitary adenomas (5%) and 1 among 5 in pituitary epithelial cysts (20%). In addition, there were 4 cases in which histologic sections of the surgical specimen showed only the feature of "cholesterol granuloma reaction", in the absence of tumorous epithelial components. "Cholesterol granuloma reaction" is thought to develop as a secondary reaction to hemorrhage or tissue necrosis (pituitary adenomas), or to keratinization (craniopharyngiomas). In occasions in which surgical specimen show only a feature of "cholesterol granuloma reaction", making the final diagnosis is necessary to be careful, taking account of other lesions as well as craniopharyngiomas.