Pituitary tumors account for approximately 15% of intracranial tumors.
Unlike benign pituitary adenomas, pituitary adenocarcinomas are usually endocrinologically-inactive ('silent') and rapidly growing tumors with a high mortality index. Some may secrete sex hormones.
Localized invasion of the sella turcica, ventricles and leptomeninges is common.
Clinically affected dogs present with neurological symptoms, anorexia and rapid clinical deterioration.
Blood tests may reveal low serum gonadotropin, LH, FSH and testosterone levels but are otherwise unrewarding. A low- and high-dose dexamethasone suppression tests may be used as a preliminary test for differentiating pituitary-dependent hyperadrenocorticism from adrenal-tumor hyperadrenocorticism.
A tentative diagnosis can be established with cranial imaging using CT or MRI, but a definitive diagnosis requires histopathological analysis of biopsies obtained via hypophyseal biopsy or exploratory craniotomy.
A differential diagnosis would include distemper, lymphoma, hypothalamic-pituitary trauma, dorsally expanding cysts, inflammatory granuloma, lymphocytic hypophysitis, congenital malformations such as empty sella syndrome and neoplasms such as infundibuloma, neurofibrosarcoma, xanthogranuloma, craniopharyngioma, oligodendroglioma, pituitary adenoma and metastatic tumors such as metastatic mammary carcinoma, lymphoma, malignant melanoma and pancreatic carcinoma.
Salvage hypophysectomy may provide resolution of symptoms, but survival rates in reported cases is poor.
- Uni of Pennsylvania
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