Syndrome of inappropriate antidiuretic hormone secretion in a cat with a putative Rathke’s cleft cyst

Abstract

An 11-year-old spayed female domestic shorthair cat was evaluated for anorexia, lethargy and weight loss of 6 days' duration. Bilateral mydriasis, absent menace response, slow-to-absent pupillary light reflexes, bilateral retinal detachment, intermittent horizontal nystagmus, intermittent ventral strabismus and systemic hypertension were present. Biochemical analysis revealed severe hyponatremia, severe hypochloremia and mild hypokalemia. Multifocal central nervous system disease was suspected based on optic, trigeminal sensory (ophthalmic branch), vestibulocochlear and possible oculomotor nerve dysfunction. Thoracic radiographs showed mild cardiomegaly without evidence of congestive heart failure. Ultrasound revealed mild pleural and peritoneal effusion. A cause of the severe hyponatremia was not identified, and it persisted despite fluid therapy. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) was suspected as the cause of hyponatremia. Humane euthanasia was elected owing to continued clinical decline. Serum hyposmolality, urine hyperosmolality, natriuresis and lack of confirmed renal, thyroid and pulmonary disease aided in the presumed diagnosis of SIADH. Post-mortem histopathology of the brain revealed degeneration of the hypothalamus and optic tracts, along with a prominent fluid-filled craniopharyngeal duct (putative Rathke's cleft cyst) separating the pars distalis and the pars intermedius. The hypothalamic degeneration, possibly secondary to a Rathke's cleft cyst, was hypothesized to be the cause of presumptive SIADH in the patient. Although rare in occurrence, Rathke's cleft cyst should be included as a differential diagnosis in dogs and cats with signs of pituitary dysfunction.

A Recurrent Suprapituitary Ependymal Cyst Managed by Endoscopy-Assisted Transsphenoidal Surgery in a Canine: A Case Report

“…First, MRI strongly indicated that the intrasellar component of the lesion was etiologically associated with the pituitary gland. Second, the features of the lesion appeared similar to those of RCCs described in human (32–34) and veterinary (31) medicine. In addition, although we performed cytological analysis only after the surgery (which involved removal of the hypophysis), the findings did not exclude a neuroendocrine origin.…”

“…In the present report, we describe a suprapituitary ependymal cyst that was treated by endoscopic transsphenoidal surgery in a mixed-breed dog. Current literature pertaining to veterinary medicine does not document any cases involving such lesions in dogs, although one study has described Rathke's cleft cyst (RCC) secreting antidiuretic hormone in a cat (31). In human medicine, RCCs are benign lesions that arise within the sella, between the anterior and posterior lobes of the pituitary gland, and can compress the surrounding structures of the sella turcica (optic chiasm and pituitary gland); RCCs are incidentally detected in 4–33% human autopsies (32).…”

“…The most common sites of intracranial cysts in animals include the fourth ventricle and cerebellopontine angle (2, 6, 8, 10, 12, 14–16) and the area above the quadrigeminal plate (4–7, 9). There are individual reports of cysts located in the brainstem (6, 9, 11, 13); cerebellum (3); and frontal (11), diencephalic (1), and hypophyseal (31) regions. Lesions involving the cerebellar, medullary, and fourth ventricular regions can be best approached from the caudal direction (suboccipital approach, e.g., cystoperitoneal shunting).…”

Congenital pituitary cyst resulting in adipsic central diabetes insipidus and secondary hypernatremia in a cat

“…34 Clinical syndromes associated with these malformations include dwarfism and aggressive behavior in dogs, and syn drome of inappropriate ADH secretion in one cat. [35][36][37][38] This is the first report of a pituitary cyst resulting in adipsic CDI in the veterinary literature.…”

Hypochloremia in cats – prevalence and associated diseases

“…Other commonly cited causes include the administration of fluids poor in Cl -(e. g. sodium bicarbonate) and chronic respiratory acidosis. Feline hypochloremia has also been reported in many diseases in cluding kidney disease (17,18), acute tumor lysis syndrome (5), anemia (11), urethral obstruction (26), diabetes mellitus (4,7,8,37), metabolic alkalosis (22), systemic inflammatory response (9), hyperadrenocorticism (36), hyperaldosteronism (12), hypoadrenocorticism (30), acute congestive heart failure (21), refeeding syndrome (3) and syndrome of inappropriate antidiuretic hormone secretion (10). Although the application of a correction formula (Clcorrected = Clmeasured × Na + normal / Na + measured ) is important to exclude low plasma Clconcentrations caused by Cl --dilution e.g.…”