Feline Pituitary and Adrenal Neoplasia Study Guide

Overview and Clinical Importance

Pituitary and adrenal neoplasia in cats represents an uncommon but clinically significant group of endocrine disorders. Unlike dogs where hyperadrenocorticism (HAC) is one of the most common endocrinopathies, feline HAC accounts for fewer than 200 cases reported in the veterinary literature. However, understanding these conditions is essential for NAVLE preparation because their clinical presentation, diagnostic approach, and treatment differ substantially from canine patients.

Approximately 80% of feline HAC cases are pituitary-dependent (PDH), with the remaining 20% caused by adrenal tumors. The concurrent presence of diabetes mellitus in 80-90% of affected cats makes these cases particularly challenging. Additionally, up to one-third of cats with HAC develop feline skin fragility syndrome (FSFS), a pathognomonic dermatologic manifestation requiring careful handling during diagnosis and treatment.

Etiology and Pathophysiology

Pituitary-Dependent Hyperadrenocorticism (PDH)

PDH accounts for approximately 80% of spontaneous feline HAC cases. These tumors arise from ACTH-secreting cells (corticotrophs) in the pars distalis or pars intermedia of the adenohypophysis. The vast majority (greater than 90%) are benign adenomas, with pituitary carcinomas being rare. Excessive ACTH secretion results in bilateral adrenal hyperplasia and chronic hypercortisolemia.