Unilateral phaeochromocytoma in a dog with pre-existing, long-standing primary hypoadrenocorticism: a case report

BACKGROUND: This is a rare occurrence of a phaeochromocytoma in a dog with pre-existing, long-standing primary hypoadrenocorticism that underwent successful surgical intervention with a favourable outcome. The objective of this case report is to describe the diagnosis, management and outcome for unilateral phaeochromocytoma in a dog with pre-existing chronic adrenal insufficiency and atrophy. CASE PRESENTATION: A 14-year-old neutered female Jack Russell Terrier had a 1-week history of hyporexia, lethargy and progressive weight loss of 1.4 kg in 5 months. Computed tomography identified a left adrenal gland nodule of 5.3 mm diameter, several 1 to 2 mm soft tissue attenuating pulmonary nodules, and a large 65 mm diameter intraparenchymal right renal mass. A left adrenalectomy and right nephroureterectomy were performed. Histopathology with immunohistochemistry confirmed the diagnosis of phaeochromocytoma and renal cell carcinoma. The dog continued treatment for hypoadrenocorticism and was in good clinical condition at 3, 7, and 11 weeks postoperative follow-up. CONCLUSIONS: This report details a unique finding of phaeochromocytoma in a dog with long-standing adrenocortical insufficiency and highlights the need for consideration of this as a differential for adrenal nodules, even in dogs with known cortical insufficiency and adrenal gland atrophy.