Table 1.

Histological and molecular characteristics of pineal region tumors. PC = pineocytomas; PPTID = pineal parenchymal tumors of intermediate differentiation; PB = pinealoblastoma; DMT = desmoplastic myxoid tumor; PTPR = papillary tumor of the pineal region, TBD: to be defined.

Histotypes	WHO Grade	Frequent Age at Diagnosis	Mitotic Count (mitosis/10HPF)	Ki67/Mib1 LI (%)	Most Frequent Molecular Alterations
PC	1	adult	<0–1	1–2	n.s.
PPTID	2	adult	<5	6–10	KBTBD4 (insertion); ATRX loss of function
	3		5	10–20
PB (subtypes)
PB-miRNA1	4	older children or young adult	High mitotic count	20–25% and up to 50 or more	DICER1, DROSHA, DGCR8 (loss of function)
PB-miRNA2					DICER1, DROSHA (loss of function)
PB-MYC/FOXR2		Infant or young children			FOXR2 overexpression; MYC activation
PB-RB1					RB1 loss of function
DMT-SMARCB1-mut	TBD	young adult	<0–1	3	SMARCB1 loss of function
PTPR	2	young adult	<2–3	2–3	PTEN mutation; PI3K alteration
	3		≥3	≥10