Definition
- Essential:
- Demonstration of pineal parenchymal differentiation by histopathological and immunophenotypic features (e g. positivity for synaptophysin) AND
- Increased proliferative/mitotic activity AND
- Absence of criteria qualifying for the diagnosis of pineoblastoma AND
- Pineal region location AND
- (For unresolved cases) DNA methylation profiling
- Desirable:
- Molecular demonstration of KBTBD4 in-frame insertions
Numbers
- 41 yrs old
- M:F = 0.8:1
- 45% of all pineal parenchymal tumours
Localisation
- Pineal region
Cell origin
- Pinealocytes like pineocytoma
Grading
- Grade 2:
- Ki67: 5%
- Grade 3:
- Ki67: 11%
- Definition for high grade (have not been fully validated):
- Showing < 6 mitoses per 10 high-power fields but no or only rare expression of NFP OR
- Showing > 6 mitoses per 10 high-power fields and NFP expression in numerous cells
Histopathology
Macroscopy
- Similar to pineocytoma
Microscopy
- They can grow in a
- Diffuse pattern (neurocytoma-like or oligodendroglioma-like),
- Lobules pattern (endocrine- like)
- Mixture of both
- Neoplastic cells usually harbour round nuclei showing mild to moderate atypia and a so-called salt-and-pepper chromatin.
- Cytoplasm of cells is more easily distinguishable than in pineoblastoma
- Pineocytomatous rosettes
(A) Neurocytoma-like appearance in a pineal parenchymal tumour of intermediate differentiation. Tumour with moderate cellularity and round nuclei harbouring salt-and-pepper chromatin; the fibrillary background is characterized by small pseudorosettes; larger pseudorosettes, as seen in pineocytomas, are not observed.
(B) Pseudolobulated pineal parenchymal tumour of intermediate differentiation. In this tumour, large fibrous vessels delineate poorly defined lobules of neoplastic cells.
(A) Diffuse pineal parenchymal tumour of intermediate differentiation. This tumour is composed of round cells with a conspicuous cytoplasm and round to oval nuclei with delicate chromatin.
(B) Pleomorphic cells in a low-grade pineal parenchymal tumour of intermediate differentiation.
Immunophenotype
- Synaptophysin positive
- NFP, chromogranin-A variable
- Nuclear NeuN negative
- ASMT positive (more than pineoblastoma)
Genetic profile
- Small in-frame insertions of KBTBD4
- Expression of four genes (PRAME, CD24, POU4F2, and HOXD13) in high-grade PPTID was high in pineoblastoma and this tumour but low in pineocytoma
- No genetic susceptibility
Clinical presentation
- Compression of pineal s(x)
- Cerebral aqueduct:
- Obstruction HCP
- Papilledema
- H/A
- Ataxia
- Impaired vision
- N/V
- Brain stem
- Tectal plate compression: Parinaud syndrome
- Loss of upward gaze
- Cerebellum
- Dizziness
- Tremor
- Endocrine
- Diabetes insipidus
- Present with DI because it infiltrates the floor of 3rd ventricle affecting the pituitary
- Precocious puberty
- Acute clinical presentation can be due to tumour apoplectic
Radiology
CT
- note circumferential "exploded" pattern of Calcification
MRI
Prognosis
- Ki67 index is a good predictor of prognosis
- Great variability
- 22% Some can show local and delayed recurrence
- Progression to high grade tumour
- 10% Risk of craniospinal dissemination
- Low grade (grade 2)
- 5-year overall survival rate was 74%.
- Recurrences 26%
- Median overall survival: 165 months (vs 77 months for pineoblastoma)
- Median progression free survival of 93 months (vs 46 months for pineoblastoma)
- Risk of spinal dissemination: 10%
- High grade: (grade 3)
- 5-year overall survival rate was 39%.
- Recurrence 56%
- Risk of spinal dissemination: 28%
Made with Bullet