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Pineal Tumors





Germ Cell Tumors

Cellular Origin

Tumors arise from germ cells or less differentiated embryonal cells which migrate through the embryo. 

These cells localize in the gonadal ridges but may migrate to other midline sites, such as the brain.  This explains why cells of similar histologies to those in the pineal region may be found in the mediastinum and the retroperitoneum. 


Tumor Histology 

It is common for a tumor to have more than one different histological subtype, making it difficult to obtain accurate figures about the prevalence of certain tumor types.

Tumor type

Macroscopic Properties

Microscopic Properties


Poorly circumscribed


Cysts are uncommon


Gray/pink color


Large polygonal cells


Separated into lobules by blood vessels and connective trabeculae


Mitotic figures


Embryonal carcinoma

Large, hemorrhagic, necrotic tumors


Grow in solid sheets or form large tubular or papillary structures



  • loose and edematous OR
  • fibrous and hyalinized


Malignant-appearing epithelial cells


Coarse, irregular nuclear membrane


Mitotic figures


Granular, hemorrhagic, necrotic tumors


May be circumscribed, but often invades adjacent brain:

  • tentorium
  • falx
  • superior sagittal sinus


2 cell types:

1. cytotrophoblastic cells:

  • uniform
  • distinct borders
  • vesicular nucleus

2. syncytiotrophoblast cells

  • multinucleated
  • eosinophilic cytoplasm
  • vacuoles




Round or lobulated


Solid and cystic areas



Components of all 3 germ layers:


  • Endoderm: GI and respiratory tissues, mucous-secreting glands
  • Mesoderm: bone, cartilage, muscle
  • Ectoderm: squamous epithelium, neural tissue


Pink/ white/ gray colour


Cysts of gelatinous material


Hemorrhagic and necrotic (occasionally)






Scant, ill-defined cytoplasm


Similar appearance to medulloblastoma cells


Homer-Wright rosettes


Highly cellular


Poorly differentiated




Less cellular than pineoblastoma





Large cell nuclei


Often observe transition features between pineoblastoma and pineocytoma


Evidence for astrocytic and ganglion cell differentiation


Occasional Homer-Wright rosettes


Variable mitotic figures


May be poorly differentiated




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