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Pituitary adenoma
Introduction
- Estimates of incidence of brain neoplasia vary from 2-3% of dogs to 15 in 100,000.
- Pituitary adenomas are a common brain neoplasm. They account for approximately 13% of all intracranial tumours in dogs.
- They may be non-functional, or cause endocrine disorders.
- The possible endocrine disorders associated with pituitary adenoma include pituitary-dependent hyperadrenocorticism (hypersecretion of ACTH), diabetes insipidus or acromegaly.
- The most common type in dogs is corticotroph adenoma (hypersecretion of ACTH).
- Signs: neurological signs, where present, include:
- Pacing.
- Lethargy.
- Wandering.
- Head-pressing.
- Hiding.
- Tight circling.
- Trembling.
- Seizures.
- Blindness.
- Positional nystagmus.
- Symmetric tetraparesis.
- Anorexia.
- Diagnosis: signs, laboratory tests, MRI, CT scan.
- Treatment: pituitary ablation (surgical, radiotherapy).
- Prognosis: guarded but depends on size.
Presenting signs
- Pituitary-dependent hyperadrenocorticism Hyperadrenocorticism if corticotroph.
- 30% or more of dogs with pituitary-dependent hyperadrenocorticism go on to develop neurological signs 1-2 years after the start of treatment for hyperadrenocorticism.
- Pacing, lethargy, wandering, hiding, head pressing and trembling.
- Seizures Seizures.
- Positional nystagmus.
- Central diabetes insipidus Diabetes insipidus.
- Acute blindness with dilated non-responsive pupils.
- Acromegaly Acromegaly, with circling and seizures.
- Hypopituitarism.
Geographic incidence
- Worldwide.
Age predisposition
- Usually over 6 years of age (median age ~10 years).
Breed/Species predisposition
- Poodle:
- Standard Poodle: Standard.
- Miniature Poodle: miniature.
- Toy Poodle: Toy.
- Dachshunds Dachshund.
- Terrier breeds.
- Beagles Beagle.
- German Shepherds German Shepherd Dog.
- Brachycephalic breeds.
- Irish setter Irish setter.
- Basset Hound Basset Hound.
- Bichon Frise Bichon Frise.
Cost considerations
- Medical treatment for hyperadrenocorticism is expensive.
Special risks
- Self-inflicted trauma from visual impairment, aimless wandering, etc.
- Status epilepticus Status epilepticus.
Pathogenesis
Etiology
- Various tumor types.
- Chromophobe adenomas, adenocarcinomas and acidophil adenomas.
- Most adenomas associated with hyperadrenocorticism are too small to produce neurological signs.
- It is believed that pituitary corticotroph tumors result from somatic mutations that occur within the corticotroph cells (rather than by chronic stimulation from hypothalamic factors).
Predisposing factors
General
- Presently unknown.
Pathophysiology
- 30% or more are larger and may become invasive, producing neurological signs due to local compression.
- Occasionally, tumors cause hypopituitarism by mechanical or functional impairment of remaining pituitary tissue.
- Non-functional pituitary tumors cause neurological signs or hypopituitarism through compression of pituitary and brain tissue during expansion and through peritumor edema.
- Functional pituitary tumors have similar effects on pituitary and brain tissue, but also cause endocrine disorders through excessive hormone secretion (most common is pituitary-dependent hyperadrenocorticism (PDH)).
- Central diabetes insipidus is sometimes caused by interference with the synthesis of antidiuretic hormone in the supraoptic nucleus, or its release into the pars nervosa.
Timecourse
- The course is usually insidious and slowly progressive over many months up to 4-6 years in some dogs with pituitary-dependent hyperadrenocorticism.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Sanders K, Galac S, Meij B P (2021) Pituitary tumour types in dogs and cat. Vet J 270, 105623 PubMed.
- Del Magno S, Fracassi F, Grinwis G C M, Mandrioli L, Gandini G, Rossi F, Sirri R, Pisoni L, Tryfonidou M A, Meij B P (2019) Sequential Treatment of a Large Pituitary Corticotroph Neoplasm and Associated Neurological Signs in a Dog. J Am Anim Hosp Assoc 55 (2), e552-02 PubMed.
- Hansen K S, Zwingenberger A L, Théon A P, Kent M S (2019) Long‐term survival with stereotactic radiotherapy for imaging‐diagnosed pituitary tumors in dogs. Vet Rad 60 (2), 219-232 PubMed.
- Menchetti M, De Risio L, Galli G, Cherubini G B,Corlazzoli D (2019) Neurological abnormalities in 97 dogs with detectable pituitary masses. Vet Q 39 (1), 57-64 PubMed.
- Miller M A, Bruyette D S, Scott-Moncrieff J C et al (2018) Histopathologic Findings in Canine Pituitary Glands. Vet Path 55 (6), 871-879 PubMed.
- Miller M A, Owen T J, Bruyette D S, Scott-Moncrieff J C, Ramos-Vara J A et al (2018) Immunohistochemical Evaluation of Canine Pituitary Adenomas Obtained by Transsphenoida l Hypophysectomy. Vet Path 55 (6), 889-895 PubMed.
- Sawadaa H, Mori A, Lee P, Sugihara S, Oda H, Sako T (2018) Pituitary size alteration and adverse effects of radiation therapy performed in 9 dogs with pituitary-dependent hypercortisolism. Res Vet Science 118,19-26 PubMed.
- Vastenhout N,van Rijn S J, Riemers F M, Tryfonidou M A, Meij B P, Penning L C (2018) The mRNA expression of PTTG1 is a strong prognostic indicator for recurrence after hypophysectomy in dogs with corticotroph pituitary adenomas. Vet J 240, 19-21 PubMed.
- Ben-Shlomo A, Cooper O (2017) The role of tyrosine kinase inhibitors in the treatment of pituitary tumors: from bench to bedside. Curr Opin Endocrinol Diabetes Obes 24(4), 301-305 PubMed.
- Nagata N, Kojima K, Yuki M (2017) Comparison of Survival Times for Dogs with Pituitary‐Dependent Hyperadrenocorticism in a Primary‐Care Hospital: Treated with Trilostane versus Untreated. J Vet Intern Med 31 (1), 22-28 PubMed.
- Sato A, Teshima T, Ishino H, Harada Y, Yogo T, Kanno N, Hasegawa D, Hara Y (2016) A magnetic resonance imaging‐based classification system for indication of trans‐sphenoidal hypophysectomy in canine pituitary‐dependent hypercortisolism. J Small Anim Pract 57(5), 240-246 PubMed.
- Fracassi F, Corradini S, Floriano D, Boari A, Aste G, Pietra M, Bergamini P F, Dondi F (2015) Prognostic factors for survival in dogs with pituitary‐dependent hypercortisolism treated with trilostane. Vet Rec 176 (2), 49-49 PubMed.
- Marcinowska A, Warland J, Brearley M, Dobson J (2015) Comparison of two coarse fractionated radiation protocols for the management of canine pituitary macrotumor: an observational study of 24 dogs. Vet Radiol Ultrasound 56(5), 554-562 PubMed.
- Fracassi F, Mandrioli L, Shehdula D, Diana A, Grinwis G C M, Meij B P (2014) Complete Surgical Removal of a Very Enlarged Pituitary Corticotroph Adenoma in a Dog. J Am Anim Hosp Assoc 50 (3), 192-197 PubMed.
- Mamelak A N, Owen T J, Bruyette D (2014) Transsphenoidal surgery using a high definition video telescope for pituitary adenomas in dogs with pituitary dependent hypercortisolism: Methods and results. Vet Surg 43 (4),369-379 PubMed.
- van Rijn S J, Galac S, Tryfonidou M A, Hesselink J W, Penning L C, Kooistra H S, Meij B P (2014) The Influence of Pituitary Size on Outcome After Transsphenoidal Hypophysectomy in a Large Cohort of Dogs with Pituitary‐Dependent Hypercortisolism. J Vet Int Med 30 (4), 989-995 PubMed.
- Fukuoka H, Cooper O, Ben-Shlomo A, Mamelak A, Ren S G, Bruyette D, Melmed S (2011) EGFR as a therapeutic target for human, canine, and mouse ACTH-secreting pituitary adenomas. J Clin Invest 121(12), 4712-4721 PubMed.
- Auriemma E, Barthez P Y, van der Vlugt-Meijer R H, Voorhout G, Meij B P (2009) Computed tomography and low-field magnetic resonance imaging of the pituitary gland in dogs with pituitary-dependent hyperadrenocorticism: 11 cases (2001-2003). JAVMA 235 (4), P 409-414 PubMed.
- Dow S W, LeCouteur R A, Rosychuk R A W, Powers B E, Kemppainen R J, Gillette E L (2009) Response of dogs with functional pituitary macroadenomas and macrocarcinomas to radiation. J Small Anim Pract 31 (6), 287-294.
- de Fornel P, Delisle F, Devauchelle P, Rosenberg D (2007) Effects of radiotherapy on pituitary corticotroph macrotumors in dogs: A retrospective study of 12 cases. Can Vet J 48(5),481-486 PubMed.
- Hanson J M, Teske E, Voorhout G, Galac S, Kooistra H S, Meij B P (2007) Prognostic factors for outcome after transsphenoidal hypophysectomy in dogs with pituitary-dependent hyperadrenocorticism. J Neurosurg 107(4), 830-840 PubMed.
- Kent M S, Bommarito D, Feldman E, Theon A P (2007) Survival, Neurologic Response, and Prognostic Factors in Dogs with Pituitary Masses Treated with Radiation Therapy and Untreated Dogs. J Vet Intern Med 21 (5), 1027-1033 PubMed.
- Hanson J M, van‘t Hoofd M M,Voorhout G,Teske E, Kooistra H S, Meij B P (2005) Efficacy of Transsphenoidal Hypophysectomy in Treatment of Dogs with Pituitary‐Dependent Hyperadrenocorticism. J Vet Intern Med 19 (5),687-694 PubMed.
- Ishinoa H, Haraa Y, Takekoshib S, Teshimac T, Teramotod A, Osamurab R Y, Tagawaa M (2001) Ki-67 and minichromosome maintenance-7 (MCM7) expression in canine pituitary corticotroph adenomas. Domestic Animal Endocrinology 41 (4),207-213 PubMed.
- Greco D S et al (1999) Concurrent pituitary and adrenal tumors in dogs with hyperadrenocorticism - 17 cases (1978-1995). JAVMA 214 (9), 1349-1353 PubMed.
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Other Sources of Information
- Lunn K L, Boston S E (2020) Cancer chemotherapy. In: Small Animal Clinical Oncology. 6th edn. Eds Withrow & MacEwen. Elsevier Saunders, St. Louis. pp 565-56.
- Moore S A, O’Brien D P (2008) Canine pituitary macrotumours. Compendium pp 33-41.