Granular cell tumor of the pituitary region

Last revised by Frank Gaillard on 21 Feb 2022

Granular cell tumors of the pituitary region, also known as pituitary choristomas, are rare low-grade tumors of the posterior pituitary and infundibulum. 

Care must be taken when reading older literature as granular cell tumors of the pituitary region, and alternative names including pituitary choristoma and Abrikossoff tumor, have in the past been thought to be, at least by some, equivalent to a pituicytoma.

In the 5th edition (2021) of the WHO classification of CNS tumors, these tumors are grouped together with pituicytomas and spindle cell oncocytomas of the pituitary gland as "most likely representing a spectrum of a single nosological entity" unified by all having expression of thyroid transcription factor 1 (TTF-1) 4. Having said that, they go on to describe distinctive histological features, as such we continue to discuss these two other entities separately. 

Granular cell tumors of the pituitary are composed of sheets of densely packed large polyhedral cells, with abundant eosinophilic cytoplasm filled with periodic acid-Schiff–positive granules 1,2,4

Immunohistochemistry shares some similarities to pituicytomas 3:

  • TTF1: positive nuclear staining
  • S100: positive
  • vimentin: positive
  • alpha-1-antitrypsin: positive
  • GFAP: usually negative

Granular cell tumors of the pituitary region are usually located in the suprasellar region, having arisen from the infundibulum, or less frequently from the posterior pituitary and thus located with the sella 3. When small, they can be seen localized to the pituitary stalk 3

Granular cell tumors of the pituitary region are usually not calcified 3

Heterogeneous signal mass with variable contrast enhancement 3

When small, and clearly localized to the infundibulum the main differential includes: 

When larger, then it is difficult to anticipate the diagnosis with other diagnoses being far more common, including: 

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