Adrenal adenocarcinoma

From Dog
Photomicrograph of an adrenal adenocarcinoma, showing neoplastic cells are in the upper part of the figure, and normal tissue is at the bottom and right parts of the figure[1]

Adrenal adenocarcinoma are the more common form of canine adrenal tumors compared with adrenal carcinomas, and a contributing cause to canine hyperadrenocorticism.

Of the adrenocortical tumors, up to 80% are malignant adenocarcinomas which occur unilaterally and cause adrenal atrophy in the contralateral adrenal due to glucocorticoid suppression. These tumors may or may not be endocrinologically active[2].

In most dogs, the hormone produced and secreted by these tumors is cortisol. Yet, in some cases adrenocortical tumors produce mineralocorticosteroids, mainly aldosterone, or, very rarely, its active precursor deoxycorticosterone[3].

Adenocarcinomas of the adrenal are frequently locally invasive and in advanced cases metastasize via localized vein infiltration, with dissemination to the vena cava and liver[4], particularly if tumors are ≥ 1.5 cm in length (as measured ultrasonographically or grossly on post-mortem[5].

In rare cases, adrenal adenocarcinoma can be present with concurrent adrenal pheochromocytoma[6] as well as developing as a secondary tumor which develops as a result of metastasis from other primary organ sites such as the lung[7].

Clinical signs of these tumors are usually related to symptoms of hyperadrenocorticism and diagnosis can be presumptive on ultrasonographic examination of the adrenals.

Definitive diagnosis requires adrenal biopsy and histological examination.

Treatment is usually curative with adrenalectomy[8], but in advanced cases where metastasis is evident, the prognosis is guarded.

References

  1. Gójska-Zygner O et al (2012) Functioning unilateral adrenocortical carcinoma in a dog. Can Vet J 53(6):623-625
  2. Bailey DB & Page RL (2007) Tumors of the Endocrine System. In: Withrow SJ, Vail DM, editors. Withrow & MacEwen’s Small Animal Clinical Oncology. 4th ed. St Louis, Missouri: Saunders Elsevier. pp:583–609
  3. Feldman EC & Nelson RW (2004) Canine hyperadrenocorticism (Cushing’s syndrome) In: Feldman EC, Nelson RW, editors. Canine and Feline Endocrinology and Reproduction. 3rd ed. St. Louis, Missouri: Saunders. pp:252–357
  4. Machida T et al (2008) Aldosterone-, corticosterone- and cortisol-secreting adrenocortical carcinoma in a dog: case report. J Vet Med Sci 70(3):317-320
  5. Massari F et al (2011) Adrenalectomy in dogs with adrenal gland tumors: 52 cases (2002-2008). J Am Vet Med Assoc 239(2):216-221
  6. Hylands R (2005) Veterinary diagnostic imaging. Malignant pheochromocytoma of the left adrenal gland invading the caudal vena cava, accompanied by a cortisol secreting adrenocortical carcinoma of the right adrenal gland. Can Vet J 46(12):1156-1158
  7. Castellano MC et al (2006) Primary pulmonary adenocarcinoma metastatic to the uvea, brain and adrenal gland in a dog. J Vet Med A Physiol Pathol Clin Med 53(4):194-197
  8. Anderson CR et al (2001) Surgical treatment of adrenocortical tumors: 21 cases (1990-1996). J Am Anim Hosp Assoc 37(1):93-97