Expression of O⁶‐methylguanine DNA methyltransferase (MGMT) and immunohistochemical analysis of 12 pineal parenchymal tumors

Abstract

Pineal parenchymal tumors (PPTs) are rare neoplasms which occupy less than 1% of primary central nervous system tumors. Because of their rare incidence, the previous reports on PPTs are limited in number and the useful molecular markers for deciding the histological grading and even selecting chemotherapy are undetermined. In this study,

Histopathologic review of pineal parenchymal tumors identifies novel morphologic subtypes and prognostic factors for outcome

“…Although sensitive molecular markers of PPT have been identified in several small case series, the generalizability of these markers across PPT histologies is unclear. [35][36][37][38][39][40] Furthermore, it is unknown whether PPTs exist on a continuum; although there have been 2 reports of low-grade pineal neoplasms transforming to pineoblastomas and one case of pineocytoma disseminating to the leptomeninges, it remains to be established if these are indicative of true tumor biology. [41][42][43] The evolving understanding of pathological features and modifications in the classification scheme also accounts for some of the discrepancies in the literature.…”

Twenty-seven cases of pineal parenchymal tumours of intermediate differentiation: mitotic count, Ki-67 labelling index and extent of resection predict prognosis

“…Most recently, mitotic count and proliferative activity of papillary tumours of the pineal region have been detected as predictive factors for recurrence 27. MIB LI has been confirmed as a prognostic factor in a number of recent studies 3 18 19 27–29. Fèvre-Montange et al 26 reported that Ki67 LI may be helpful in distinguishing between grade II (mean 5.2) and grade III (mean 11.2) PPTID.…”

“…Also, grade II and grade III might present ++ NF staining and need to be further differentiated by mitotic count 5 7. Discrepancies of NF staining have been increasingly reported by recent histopathological studies and other PPTID specific markers have been proposed, such as MIB LI and Ki-67 LI, in the past decades 12 18 19 26. Most recently, mitotic count and proliferative activity of papillary tumours of the pineal region have been detected as predictive factors for recurrence 27.…”

“…This classification has been widely applied to date. However, inconsistencies of tumour imaging and clinical outcome with this grading system, especially with NF staining, have been frequently reported by other authors 14 18 19. In addition, previous studies did not offer any systematic discussion of proper PPTID management.…”

Commentary: Malignant Pineal Parenchymal Tumors in Adults: A National Cancer Database Analysis

“…17,18 In a large cohort of patients with PPTID, Chalif et al found lack of survival advantage from chemotherapy 7 -these findings are consistent with a systematic review of 127 patients with PPTID 15 and reports of retained O 6 -methylguanine DNA methyltransferase promoter methylation status, which is likely to influence response to chemotherapy. 19 The authors determined that radiotherapy was independently associated with significantly increased survival; however, when radiotherapy was used as an adjuvant for surgically treated patients, it was only associated with significantly increased 5-year OS in patients with PPTID WHO grade 3. 7 These findings from Chalif et al 7 Resection group was associated with significantly higher PFS rates than the biopsy group (1-y 97% and 90% and 5-y 89% and 75%, respectively; P < .05).…”