Pineal parenchymal tumors

Pineal parenchymal tumours comprise a group of related tumours ranging from the relatively benign to the highly malignant. There are four types in the WHO classification:

• pineocytoma
  • 14-30% of pineal parenchymal tumours ²
  • mature well-differentiated tumour
  • WHO grade I
• pineal parenchymal tumour with intermediate differentiation
  • 20-62% of pineal parenchymal tumours ²
  • WHO grade II/III
• papillary tumour of the pineal region
  • yet to be graded but probably equivalent to WHO grade II/III ²
• pineoblastoma
  • 24-50% of pineal parenchymal tumours ²
  • malignant, primitive tumours
  • WHO grade IV

As you can tell from the proportions given above there is wide variation in the reported figures from series to series, which probably reflects the overall rarity of these tumours (and thus small series) and variability in the grading and terminology used.

Terminology

The term pinealoma was historically used to refer to both pineal parenchymal tumors and germinomas ³. This term has since fallen in popularity in the last several decades.