Granular cell tumour of the pituitary region, also known as a pituitary choristoma, are rare low-grade tumours of the posterior pituitary and infundibulum.
Care must be taken when reading older literature as granular cell tumours of the pituitary region, and alternative names including pituitary choristoma and Abrikossoff tumour, have in the past been thought to be, at least by some, equivalent to a pituicytoma, but in fact represent a histologically separate entity, recognised in the current (2016) WHO classification of CNS tumours 3.
Granular cell tumours 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 tumours 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 localised to the pituitary stalk 3.
Granular cell tumours of the pituitary region are usually not calcified 3.
Heterogeneous signal mass with variable contrast enhancement 3.
When small, and clearly localised 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:
- 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
Pituitary region masses
- pituitary adenoma (commonest in the adult population)
- optic pathway glioma
- dermoid (CNS) / epidermoid / intracranial teratoma
- pituitary metastases
- granular cell tumour of the pituitary (pituitary choristoma)
- pilocytic astrocytoma of the neurohypophysis (infundibuloma)
- cellular infiltrates
- other lesions