Pituicytomas are rare tumours arising from pituicytes, a specialised glial cell in the neurohypophysis and infundibulum of the pituitary gland. There is much confusion in the literature as to what exactly a pituicytoma is, with the term used to synonymously particularly in older literature by some authors for a number of other tumours (now recognised to be separate lesions, including 1,3-4:
- granular cell tumour of the pituitary (aka pituitary choristoma)
- pilocytic astrocytoma of the neurohypophysis (aka infundibuloma)
Peak Incidence is in the 5th decade, with no cases less than 20 years old. There is a recognised female predilection with M:F ratio of 1:2
Clinical presentation is either from endocrine dysfunction (amenorrhea, galactorrhea, infertility, diabetes insipidus, panhypopituitarism) or from compression of adjacent structures, typically the optic chiasm. Many are asymptomatic, with the lesion only found incidentally.
Pituicytomas are considered WHO Grade 1 tumours and are usually indolent.
Macroscopically these tumours are well circumscribed, soft to medium consistency with a gray to yellow homogeneous or granular cut surface. Necrosis and cystic degeneration are uncommon.
Histologically they are fibrillary astrocytomas, with rich blood supply. The cells are spindle or stellate in shape and syncytial fibrillary cytoplasm 1. They stain diffusely for S-100 and vimentin. GFAP and EMA are variably positive 1. Ki-67 is usually less than 2% 1.
Typically these masses a homogeneously enhancing, either with the pituitary fossa or in the suprasellar region. Size is variable, ranging from a few millimetres to a few centimetres.
- T1 : iso intense solid mass, posterior pituitary bright spot often absent
- T1 C+ (Gd) : bright contrast enhancement
- T2 : heterogenous , hypo intense to iso intense
Pituicytomas have a rich capillary network, accounting for their usual contrast enhancement and propensity to bleed at surgery. They receive their blood supply form the normal and extensive supply to the pituitary gland, including the meningohypophyseal trunk and superior hypophyseal arteries.
Treatment and prognosis
As the tumours are benign and slow growing, if asymptomatic then expectant management is sufficient. If mass effect is present then resection may be required. Caution should be exercised as these tumours are highly vascular which my lead to difficulties with a routine transphenoidal approach.
Complete resection can be difficult due to the structures involved and local recurrence is common 1.
- 1. 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
- 2. Swaab DF. The human hypothalamus, Handbook of clinical neurology. Neuropathology of the human hypothalamus and adjacent brain structure / Dick F. Swab. Elsevier. (2004) ISBN:0444514902. Read it at Google Books - Find it at Amazon
- 3. 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
- 4. Saleem SN, Said AH, Lee DH. Lesions of the hypothalamus: MR imaging diagnostic features. Radiographics. 27 (4): 1087-108. doi:10.1148/rg.274065123 - Pubmed citation
- 5. Shah B, Lipper MH, Laws ER et-al. Posterior pituitary astrocytoma: a rare tumor of the neurohypophysis: a case report. AJNR Am J Neuroradiol. 2005;26 (7): 1858-61. AJNR Am J Neuroradiol (full text) - Pubmed citation
Synonyms & Alternative Spellings
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|Astrocytoma of the posterior pituitary||✓|