Pineal parenchymal tumor of intermediate differentiation: imaging spectrum of an unusual tumor in 11 cases

Abstract

Pineal parenchymal tumor of intermediate differentiation (PPTID) was recognized in the 2007 World Health Organization (WHO) classification as a new pineal parenchymal neoplasm, intermediate in malignancy (WHO grade II or III) between pineocytoma (grade I) and pineoblastoma (grade IV). The imaging spectrum of this new tumor has not been previously delineated. We describe the imaging spectrum in 11 pathologically proven PPTIDs and identify findings that may suggest the preoperative diagnosis of this newly recognized entity. Electronic medical records over the last 9years and teaching files between the years 1985 and 1995 were searched for atypical pineal lesions. Additional cases were added from the teaching files of contributing authors. Imaging studies in nine patients (9/11) showed bulky, aggressive pineal region masses with local brain invasion; two patients (2/11) demonstrated circumscribed pineal masses. Two patients had spinal metastases at presentation. On computed tomography (CT), five patients had classic "exploded" calcifications characteristic of pineal parenchymal tumors. All tumors were heterogeneously hypointense on T1WIs and heterogeneously hyperintense on T2WIs. Post-contrast scans showed marked heterogeneous (10/11) or uniform (1/11) enhancement. Cystic foci were identified in eight cases. Intratumoral hemorrhage was present in one case. While no singular neuroimaging feature is pathognomonic of PPTID, these tumors are usually larger, demonstrate local invasion, and appear much more heterogeneous than pineocytoma. Because PPTIDs have a higher grade and increased potential for recurrence as compared to pineocytomas, it is important to consider this diagnosis as shorter follow-up, and adjuvant therapy may be indicated in selected cases.