MR DIFFERENTIATION OF ADAMANTINOUS AND SQUAMOUS-PAPILLARY CRANIOPHARYNGIOMAS

PURPOSE: To determine MR criteria for differentiating adamantinous fro m squamous-papillary craniopharyngiomas. METHODS: The MR imaging featu res of 42 histologically proved craniopharyngiomas (25 adamantinous, 1 5 squamous-papillary, and two mixed subtypes) were examined with multi planar T2-weighted and noncontrast and contrast-enhanced T1-weighted i maging. Differences in the MR features of both subtypes were evaluated retrospectively. RESULTS: The adamantinous craniopharyngioma is a mix ed solid-cystic or mainly cystic lobulated suprasellar or intrasellar/ suprasellar tumor occurring in children and adults, typically with lar ge nonenhancing hyperintense cysts on T1-weighted images. The squamous -papillary craniopharyngioma is a predominantly solid or mixed solid-c ystic suprasellar tumor occurring in adults, appearing as a hypointens e cyst on noncontrast T1-weighted images. Calcifications and recurrent tumors are more often observed in adamantinous tumors but can be seen in squamous-papillary tumors as well. Statistically significant param eters useful for differentiating the two tumor subtypes are the encase ment of vessels, the lobulated shape, and the presence of hyperintense cysts in adamantinous tumors, and the round shape, the presence of hy pointense cysts, and the predominantly solid appearance in squamous-pa pillary tumors. CONCLUSION: Craniopharyngiomas can be divided into two clinically, histologically, and radiologically different subtypes, wh ich suggests a different pathogenesis of these two types of tumor.