Chromophobe Adenocarcinoma of the Pituitary Gland in a Ram

Diseases of the Endocrine System

“…18 Release of AVP decreases as blood pressure and volume increase and osmolarity falls to normal levels. 79,80 Water deprivation testing and response to AVP administration confirmed the diagnosis in the former case; in the latter case, the test was initiated in an effort to prove this hypothesis, but clinical deterioration required euthanasia before its conclusion. In sheep, reported levels change from 4.4 ± 0.6 pg/mL to 16.8 ± 1.0 pg/mL in hydrated and dehydrated states, respectively.…”

“…One report described a pituitary carcinoma with metastasis to submandibular lymph nodes in a cow. 97 Observations made during the postmortem gross and cytologic examinations were strongly suggestive of a pituitary chromophobe adenocarcinoma. 96,97 In the first of these reports, a ram presented with ocular abnormalities and polyuria and polydipsia, all of which were compatible with a space-occupying lesion in the area of the pituitary gland and in close proximity to the optic chiasm.…”

“…97 Observations made during the postmortem gross and cytologic examinations were strongly suggestive of a pituitary chromophobe adenocarcinoma. 96,97 Differentiation of pituitary adenoma from pituitary carcinoma can be difficult if histopathologic appearance is the sole criterion used for diagnosis. 96 Unlike in reports of endocrinologically active pituitary adenomas in small ruminants, 95,99 pituitary gland adenocarcinomas are either endocrinologically inactive or cause partial hypopituitarism.…”

“…96,97 A majority of pituitary abnormalities described in small ruminants are adenomas, 91-95 but more recently, adenocarcinomas have been reported as well.…”