Pineal parenchymal tumor of intermediate differentiation

Last revised by Frank Gaillard on 7 Jan 2022

Pineal parenchymal tumors of intermediate differentiation (PPTID) are, as the name suggests, tumors that fall between pineocytoma (well-differentiated, WHO grade 1) and pineoblastomas (poorly differentiated, WHO grade 4). They are considered WHO grade 2 or 3 tumors 4. Their radiographic appearance and biological behavior are also intermediate. 

Although these tumors are encountered at all ages, they are particularly seen in middle-aged adults (20-70 years of age) with slight female predilection, similar to that of pineocytomas 4

Pineal parenchymal tumors with intermediate differentiation have a similar macroscopic appearance to pineocytomas, appearing relatively well-circumscribed with heterogeneous cut surface 4.

Two microscopic patterns are encountered, sometimes co-existing 4:

  1. lobulated
  2. diffuse

In the lobulated pattern, poorly defined lobules are separated from each other by large fibrous vessels 4.

The diffuse pattern, on the other hand, is reminiscent of oligodendrogliomas and/or central neurocytomas, with the large pineocytomatous rosettes characteristic of pineocytomas not being evident 4.

The features of pineal parenchymal tumors with intermediate differentiation range from those of pineocytomas to those of pineoblastomas, and they are therefore not repeated here.

When faced with a well-circumscribed pineal tumor with appearances of a pineocytoma, fairly rapid growth and/or low ADC values are clues that it may, in fact, represents a pineal parenchymal tumor with intermediate differentiation. 

As these tumors may invade adjacent structures and also spread along CSF and therefore imaging of the entire craniospinal axis is therefore required 3.

Like everything else about this tumor, treatment and prognosis are intermediate falling between that of pineocytomas and of pineoblastomas

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Cases and figures

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