Giant pituitary adenoma

Giant pituitary adenoma

Epidemiology

Giant pituitary adenomas comprise about 6-10% of all pituitary tumors.

It is estimated that 5% of pituitary adenoma become invasive and may grow to gigantic sizes (>4 cm in diameter).

They are mostly clinically non-functioning adenomas and occur predominantly in males 1)

Types

Clinical

The presenting symptoms are usually secondary to compression of neighboring structures, but also due to partial or total hypopituitarismFunctioning pituitary adenomas give rise to specific symptoms of hormonal hypersecretion.

Treatment

The use of dopamine agonists is considered a first-line treatment in patients with giant macroprolactinomas. Somatostatin analogs can also be used as primary treatment in cases of growth hormone and thyrotropin producing giant adenomas, although remission of the disease is not achieved in the vast majority of these patients.

The intrinsic complexity of these tumors requires the use of different therapies in a combined or sequential way. A multimodal approach and a therapeutic strategy involving a multidisciplinary team of expert professionals form the basis of the therapeutic success in these patients 2).


The main goal of surgical treatment of giant pituitary adenoma is maximum possible tumor extirpation with minimal side effects, which can be achieved by careful preoperative planning of operative approach, based on directions of tumor extensions and invasiveness. Maximal surgical removal of giant adenomas offers best chances to control tumor growth when followed with adjuvant medical and radiation therapies 3).


While the use of endoscopic approaches has become increasingly accepted in the resection of pituitary adenomas, limited evidence exists regarding the success of this technique for patients with large and giant pituitary adenomas.

Major blood supply of giant pituitary adenomas originates from branches of the infraclinoidal portion of the internal carotid artery, different from normal anterior pituitary gland. Surgical route should depend not only on tumor shape and extension but on feeding systems 4).

The main goal of surgical treatment of giant pituitary adenoma is maximum possible tumor extirpation with minimal side effects, which can be achieved by careful preoperative planning of operative approach, based on directions of tumor extensions and invasiveness. Maximal surgical removal of giant adenomas offers best chances to control tumor growth when followed with adjuvant medical and radiation therapies 5).


In cases of progressive enlargement of residual lesions, a second endoscopic debulking of the tumor may be considered for control of the disease 6).

Outcome

Giant pituitary adenomas carry higher surgical risks despite recent advances in microsurgical and/or endoscopic surgery, and postoperative acute catastrophic changes without major vessel disturbance are still extremely difficult to predict, may manifest as postoperative pituitary apoplexy, and are associated with very poor outcomes.

Resection of both large and giant pituitary adenomas by microscopic transsphenoidal surgery may be safe and effective surgical technique with low morbidity and mortality 7).

Case series

References

1) , 2)

Iglesias P, Rodríguez Berrocal V, Díez JJ. Giant pituitary adenoma: histological types, clinical features and therapeutic approaches. Endocrine. 2018 Sep;61(3):407-421. doi: 10.1007/s12020-018-1645-x. Epub 2018 Jun 16. Review. PubMed PMID: 29909598.
3)

Sinha S, Sharma BS. Giant pituitary adenomas–an enigma revisited. Microsurgical treatment strategies and outcome in a series of 250 patients. Br J Neurosurg. 2010 Feb;24(1):31-9. doi: 10.3109/02688690903370305. PubMed PMID: 20158350.
4)

Ogawa Y, Sato K, Matsumoto Y, Tominaga T. Evaluation of Fine Feeding System and Angioarchitecture of Giant Pituitary Adenoma – Implications for Establishment of Surgical Strategy. World Neurosurg. 2015 Oct 5. pii: S1878-8750(15)01255-3. doi: 10.1016/j.wneu.2015.09.087. [Epub ahead of print] PubMed PMID: 26455764.
5)

Sinha S, Sharma BS. Giant pituitary adenomas–an enigma revisited. Microsurgical treatment strategies and outcome in a series of 250 patients. Br J Neurosurg. 2010 Feb;24(1):31-9. doi: 10.3109/02688690903370305. PubMed PMID: 20158350.
6)

Gondim JA, Almeida JP, Albuquerque LA, Gomes EF, Schops M. Giant pituitary adenomas: surgical outcomes of 50 cases operated on by the endonasal endoscopic approach. World Neurosurg. 2014 Jul-Aug;82(1-2):e281-90. doi: 10.1016/j.wneu.2013.08.028. Epub 2013 Aug 29. PubMed PMID: 23994073.
7)

Karki M, Sun J, Yadav CP, Zhao B. Large and giant pituitary adenoma resection by microscopic trans-sphenoidal surgery: Surgical outcomes and complications in 123 consecutive patients. J Clin Neurosci. 2017 Aug 1. pii: S0967-5868(16)30922-5. doi: 10.1016/j.jocn.2017.07.015. [Epub ahead of print] PubMed PMID: 28778803.
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