ISSN 2398-2969      

Pituitary adenoma

icanis
Contributor(s):

Kyle Braund


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 may be non-functional, or cause endocrine disorders.
  • The possible endocrine disorders associated with pituitary adenoma include pituitary-dependent hyperadrenocorticism, diabetes insipidus or acromegaly.
  • Signs: neurological signs, where present, include:
    • Pacing.
    • Lethargy.
    • Wandering.
    • Head-pressing.
    • Hiding.
    • Tight circling.
    • Trembling.
    • Seizures.
    • Blindness.
    • Positional nystagmus.
  • Diagnosis: signs, laboratory tests, MRI.
  • Treatment: pituitary ablation (surgical, radiotherapy).
  • Prognosis: guarded.

Pathogenesis

Etiology

  • Various different tumor types.
  • Chromophobe adenomas, adenocarcinomas and acidophil adenomas.
  • Most adenomas associated with hyperadrenocorticism are too small to produce neurological signs.

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).
  • 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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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • 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.
  • Goossens M M C et al (1998) Efficacy of Cobalt 60 radiotherapy in dogs with pituitary-dependent hyperadrenocorticism. JAVMA 212 (3), 374-376 PubMed.
  • Meij B P et al (1998) Results of transsphenoidal hypophysectomy in 52 dogs with pituitary-dependent hyperadrenocorticism. Vet Surg 27 (3), 246-261 PubMed.
  • Bertoy E H et al (1996) One-year follow-up evaluation of magnetic resonance imaging of the brain in dogs with pituitary-dependent hyperadrenocorticism. JAVMA 208 (8), 1268-1273 PubMed.

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