Granular cell tumor of the pituitary region, also known as a pituitary choristoma, 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, but in fact represent a histologically separate entity, recognized in the current (2016) WHO classification of CNS tumors 3.
Granular cell tumors of the pituitary are composed of sheets of large polyhedral cells, with abundant eosinophilic cytoplasm filled with periodic acid-Schiff–positive granules 1,2. They have only focal spindled areas (in contrast to pituicytomas). They are usually negative for GFAP 2.
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:
- pituitary macroadenoma
- pituitary metastasis
- pituitary infiltration
- optic pathway glioma
- granular cell tumor - general article
- 1. Brat DJ, Scheithauer BW, Staugaitis SM et-al. Pituicytoma: a distinctive low-grade glioma of the neurohypophysis. Am. J. Surg. Pathol. 2000;24 (3): 362-8. Am. J. Surg. Pathol. (link) - Pubmed citation
- 2. Gibbs WN, Monuki ES, Linskey ME et-al. Pituicytoma: diagnostic features on selective carotid angiography and MR imaging. AJNR Am J Neuroradiol. 2006;27 (8): 1639-42. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 3. Louis DN, Ohgaki H, Wiestler OD, Cavenee WK "WHO Classification of Tumours of the Central Nervous System. 4th Edition Revised" ISBN: 9789283244929
Related Radiopaedia articles
Pituitary region masses
- pituitary gland anatomy
- pituitary MRI - an approach
pituitary region masses
- most common pituitary region masses
- solid and enhancing pituitary region mass
- mixed cystic and solid pituitary region mass
- mostly/purely cystic pituitary region masses
- purely intrasellar pituitary mass
- pituitary region mass with intrinsic high T1 signal
- abnormal enhancement/bulkiness of the pituitary infundibulum
- enlarged sella turcica
- mnemonic: SATCHMO
- history of imaging the pituitary region
- pituitary adenoma (commonest in the adult population)
- pituitary carcinoma
- pituitary lymphoma
- optic pathway glioma
- dermoid (CNS) / epidermoid / intracranial teratoma
- spindle cell oncocytomas
- pituitary metastases
- granular cell tumor of the pituitary (pituitary choristoma)
- pilocytic astrocytoma of the neurohypophysis (infundibuloma)
- cellular infiltrates
- other lesions
- pituitary tumors