Neuroendocrine pituitary macroadenoma of a cat presenting with primary adipsia and hypernatraemia

Abstract

Case summary: A male neutered Ragdoll cat aged 11 years and 9 months presented with a 6 month history of weight loss and a 1 month history of lethargy and adipsia. A thorough clinical investigation confirmed a diagnosis of primary adipsia and hypernatraemia secondary to a non-secretory neuroendocrine pituitary macroadenoma.

Relevance and novel information: Primary adipsia is a very rare clinical entity. This report is the first to describe primary adipsia secondary to a non-secretory pituitary macroadenoma in the cat. The veterinary literature available in this field is very limited and this report adds a new differential diagnosis for cats presenting with primary hypodipsia.

Figure 1

Transverse T1-weighted magnetic resonance images at the level of the pituitary fossa (PF) with (a) pre- and (b) post-contrast (gadolinium) sequences. The suprasellar mass is hyperintense relative to the surrounding parenchyma and strongly contrast enhancing. There is a moderate degree of asymmetrical compression of the thalamus (T)

Figure 2

Transverse fluid-attenuated inversion recovery image at the level of the middle cranial fossa. An irregular hyperintensity (consistent with oedema) is seen surrounding the mass and extending into the right thalamus and corona radiata

Figure 3

A sagittal T2-weighted magnetic resonance image at the midline. An intracranial mass is seen protruding dorsally from the pituitary fossa (white arrows). The fossa is widened owing to invasion of the sphenoid bone locally. A ‘mass effect’ is resulting in mild caudal cerebellar herniation through the foramen magnum (black arrows) and compression of the interthalamic adhesion (circled). Mild caudal transtentorial herniation is also seen

Figure 4

Post-mortem examination. (a) Ventral view of the fixed brain after the tumour had been shelled out. Note the asymmetric impingement on the hypothalamus (HT) and right-sided crus cerebri (CC) with dilation of the infundibular recessus (IR) and oblique caudal compression of the optic chiasm (OC) and tracts. Scale bar = 1 cm. (b) Macroscopic appearance of the pituitary tumour. Scale bar = 0.8 cm. (c) Histology of the mass is characterised by a proliferation of neuroendocrine cells, often confined to Zellballen (ZB), surrounded by vascular septa (VS). Scale bar = 200 µm. (d,e) Tumour cells stain positive for synaptophysin (Syn) and chromogranin (Chrom). Scale bar = 100 µm. PL = piriform lobe