Pineal parenchymal tumour with intermediate differentiation

A.Prof Frank Gaillard et al.

Pineal parenchymal tumours with intermediate differentiation (PPTID) are, as the name suggests, tumours which fall between pineocytoma (well differentiated, WHO grade I) and pineoblastomas (poorly differentiated, WHO grade IV)./ They are considered WHO grade II or III tumours 2. Although these tumours are encountered at all ages, they are particularly seen in middle age adults (20-70 years of age) with slight female predilection, similar to that of pineocytomas 4

Their radiographic appearance and biological behaviour are also intermediate. They may invade adjacent structures and also spread along CSF and therefore imaging of the entire craniospinal axis is therefore required 3.

Pineal parenchymal tumours 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

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

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

The features of pineal parenchymal tumour 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 tumour with appearances of a pineocytoma, fairly rapid growth and/or low ADC values are clues that it may, in fact, represents a pineal parenchymal tumour with intermediate differentiation. 

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

Pineal region masses

The pineal region is anatomically complex and plays host to a number of unique masses and tumours as well as potentially affected by many entities seen more frequently elsewhere in the brain. 

General reading

Pathology 

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rID: 6514
Section: Pathology
Tags: cases, cases
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