History
A 12-year-old 26.0-kg spayed female Labrador Retriever was referred because of high liver enzyme activities. During the few months prior to referral, the dog had developed polyuria, polydipsia, hyporexia, and abdominal distension. The owner reported these clinical signs as progressive. A concern for hyperadrenocorticism prompted referral for further diagnostic evaluation.
On referral examination, cranial organomegaly was appreciated on abdominal palpation. Diffuse epaxial and hind limb muscle wasting was apparent. Clinically important abnormalities on serum biochemical analyses included high activities of alanine aminotransferase (592 U/L; reference range, 16 to 75 U/L) and alkaline phosphatase (831 U/L; reference range, 8 to 70 U/L) combined with hypokalemia (2.5 mEq/L; reference range, 3.4 to 4.5 mEq/L) and hypernatremia (157 mEq/L; reference range, 143 to 152 mEq/L). Hyposthenuria (urine specific gravity 1.006) was present on routine urinalysis. Abdominal radiography was performed as part of the initial investigation for the high liver enzyme activities and hepatomegaly (Figure 1).
Right lateral (A) and ventrodorsal (B) radiographic images of the abdomen of a 12-year-old 26.0-kg spayed female Labrador Retriever referred because of high liver enzyme activities, polyuria, polydipsia, hyporexia, and abdominal distension.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Right lateral (A) and ventrodorsal (B) radiographic images of the abdomen of a 12-year-old 26.0-kg spayed female Labrador Retriever referred because of high liver enzyme activities, polyuria, polydipsia, hyporexia, and abdominal distension.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Right lateral (A) and ventrodorsal (B) radiographic images of the abdomen of a 12-year-old 26.0-kg spayed female Labrador Retriever referred because of high liver enzyme activities, polyuria, polydipsia, hyporexia, and abdominal distension.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Right lateral (A) and ventrodorsal (B) radiographic images of the abdomen of a 12-year-old 26.0-kg spayed female Labrador Retriever referred because of high liver enzyme activities, polyuria, polydipsia, hyporexia, and abdominal distension.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Right lateral (A) and ventrodorsal (B) radiographic images of the abdomen of a 12-year-old 26.0-kg spayed female Labrador Retriever referred because of high liver enzyme activities, polyuria, polydipsia, hyporexia, and abdominal distension.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Diagnostic Imaging Findings and Interpretation
On the lateral radiographic projection, the liver was diffusely enlarged, extended beyond the costal arch, and had rounded and nodular margins, creating a mass effect within the cranioventral abdomen and causing caudodorsal displacement of the stomach (Figure 2). There was a poorly defined and wispy focus of mineralization within the mid-dorsal abdomen, ventral to L2 and L3, and superimposed on the tip of the 13th rib. This mineralization, although present, was more difficult to appreciate on the ventrodorsal projection due to summation with the intestine.
Same radiographic images as in Figure 1. A—The liver has rounded and nodular margins (arrows), creating a mass effect within the cranioventral abdomen. There is also a wispy focus of mineralization (circle) ventral to L2 and L3 and superimposed over the 13th rib. B—The wispy focus of mineralization (circle), although visible, is more difficult to appreciate due to summation with the intestine.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Same radiographic images as in Figure 1. A—The liver has rounded and nodular margins (arrows), creating a mass effect within the cranioventral abdomen. There is also a wispy focus of mineralization (circle) ventral to L2 and L3 and superimposed over the 13th rib. B—The wispy focus of mineralization (circle), although visible, is more difficult to appreciate due to summation with the intestine.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Same radiographic images as in Figure 1. A—The liver has rounded and nodular margins (arrows), creating a mass effect within the cranioventral abdomen. There is also a wispy focus of mineralization (circle) ventral to L2 and L3 and superimposed over the 13th rib. B—The wispy focus of mineralization (circle), although visible, is more difficult to appreciate due to summation with the intestine.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Same radiographic images as in Figure 1. A—The liver has rounded and nodular margins (arrows), creating a mass effect within the cranioventral abdomen. There is also a wispy focus of mineralization (circle) ventral to L2 and L3 and superimposed over the 13th rib. B—The wispy focus of mineralization (circle), although visible, is more difficult to appreciate due to summation with the intestine.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Same radiographic images as in Figure 1. A—The liver has rounded and nodular margins (arrows), creating a mass effect within the cranioventral abdomen. There is also a wispy focus of mineralization (circle) ventral to L2 and L3 and superimposed over the 13th rib. B—The wispy focus of mineralization (circle), although visible, is more difficult to appreciate due to summation with the intestine.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Given the clinical history and radiographic location of the mineralization, a functional adrenal gland neoplasm was considered most likely; however, other differential diagnoses included renal pelvic mineralization, a renal tumor, or retroperitoneal cyst or abscess. Neoplasia, either primary or metastatic, was considered the most likely cause of the radiographic hepatic changes; however, other differential diagnoses included nodular regeneration or an endocrine hepatopathy.
Abdominal ultrasonography was performed to delineate the origin of the mineralization and cause of the nodular hepatomegaly. Ultrasonography revealed a hyperechoic mass (4.0 X 1.2 cm) with a central region of distal acoustic shadowing present in the region of the left adrenal gland (Figure 3). The right adrenal gland was normal in size. Additionally, an echogenic mass was present within the caudal vena cava associated with the left adrenal gland, consistent with a tumor thrombus. The liver contained multiple round, variably sized, isoechoic to hypoechoic masses throughout all lobes.
Abdominal ultrasonographic images from the dog described in Figure 1. A—The left adrenal gland has a hyperechoic mass (arrow) with a central region of distal acoustic shadowing (mineralization). B—A presumed tumor thrombus (black arrows) is in the caudal vena cava (white arrow) and associated with the left adrenal mass. C—Multiple round, variably sized, iso- to hypoechoic masses (arrows) are in the liver.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Abdominal ultrasonographic images from the dog described in Figure 1. A—The left adrenal gland has a hyperechoic mass (arrow) with a central region of distal acoustic shadowing (mineralization). B—A presumed tumor thrombus (black arrows) is in the caudal vena cava (white arrow) and associated with the left adrenal mass. C—Multiple round, variably sized, iso- to hypoechoic masses (arrows) are in the liver.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Abdominal ultrasonographic images from the dog described in Figure 1. A—The left adrenal gland has a hyperechoic mass (arrow) with a central region of distal acoustic shadowing (mineralization). B—A presumed tumor thrombus (black arrows) is in the caudal vena cava (white arrow) and associated with the left adrenal mass. C—Multiple round, variably sized, iso- to hypoechoic masses (arrows) are in the liver.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Abdominal ultrasonographic images from the dog described in Figure 1. A—The left adrenal gland has a hyperechoic mass (arrow) with a central region of distal acoustic shadowing (mineralization). B—A presumed tumor thrombus (black arrows) is in the caudal vena cava (white arrow) and associated with the left adrenal mass. C—Multiple round, variably sized, iso- to hypoechoic masses (arrows) are in the liver.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Abdominal ultrasonographic images from the dog described in Figure 1. A—The left adrenal gland has a hyperechoic mass (arrow) with a central region of distal acoustic shadowing (mineralization). B—A presumed tumor thrombus (black arrows) is in the caudal vena cava (white arrow) and associated with the left adrenal mass. C—Multiple round, variably sized, iso- to hypoechoic masses (arrows) are in the liver.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Abdominal ultrasonographic images from the dog described in Figure 1. A—The left adrenal gland has a hyperechoic mass (arrow) with a central region of distal acoustic shadowing (mineralization). B—A presumed tumor thrombus (black arrows) is in the caudal vena cava (white arrow) and associated with the left adrenal mass. C—Multiple round, variably sized, iso- to hypoechoic masses (arrows) are in the liver.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Abdominal ultrasonographic images from the dog described in Figure 1. A—The left adrenal gland has a hyperechoic mass (arrow) with a central region of distal acoustic shadowing (mineralization). B—A presumed tumor thrombus (black arrows) is in the caudal vena cava (white arrow) and associated with the left adrenal mass. C—Multiple round, variably sized, iso- to hypoechoic masses (arrows) are in the liver.
Citation: Journal of the American Veterinary Medical Association 260, 6; 10.2460/javma.20.09.0539
Treatment and Outcome
Hyperaldosteronism caused by an adrenocortical mass was suspected based on the presence of an adrenal mass and hypokalemia. Cytology of a fine-needle aspirate sample of a hepatic mass lesion revealed neoplastic cells compatible with neuroendocrine carcinoma, most likely adrenocortical in origin. Baseline plasma aldosterone concentration was high (4,252 pmol/L; reference range, 14 to 957 pmol/L), consistent with a functional adrenocortical tumor. Based on the metastatic disease and tumor thrombus, medical treatment to address the hypokalemia and hyporexia was elected. The dog was prescribed spironolactone (2 mg/kg, PO, q 24 h), potassium gluconate (6 mEq, PO, q 12 h), and mirtazapine (0.6 mg/kg, PO, q 24 h). The patient was lost to follow-up.
Comments
Visualization of adrenal gland lesions with radiography is typically poor, unless the lesion is of adequate size or contains mineralization. For the dog of the present report, faint mineralization in the area of the adrenal gland was visible radiographically. This finding, along with clinical signs consistent with an endocrine disorder, prompted the use of ultrasonography to investigate for the presence of a mineralized adrenal gland mass. Based on the dimensions of the discovered mass and the presence of vascular invasion, malignancy was strongly suspected.1,2
Radiography of the liver in a patient with high liver enzyme activities has limited usefulness when evaluating for possible liver disease; however, hepatomegaly or masses, if present, can be visible on survey radiographs. In the dog of this report, palpable hepatomegaly was present on physical examination, prompting radiographic evaluation. The finding of nodular hepatomegaly made neoplasia, either primary or metastatic, the most likely differential diagnosis for such change. Ultrasonography confirmed the presence of multiple variably sized masses throughout all liver lobes.
In totality, the imaging findings were most suggestive for an adrenocortical tumor with hepatic metastasis. The finding of hypokalemia made an aldosterone-secreting adrenocortical tumor most likely. The combination of neoplastic neuroendocrine cells found on cytology of a fine-needle aspirate sample of a liver mass and a plasma aldosterone concentration over 4 times the upper reference limit confirmed the diagnosis of a metastatic aldosterone-secreting adrenocortical tumor.
Aldosterone is a hormone secreted by the adrenal cortex in response to hyperkalemia and blood volume depletion. Following release, aldosterone acts on cells in the distal tubules and collecting ducts of the kidney to promote sodium reabsorption, potassium excretion, and water retention. Consequently, aldosterone’s functions are to restore blood volume and serum potassium concentrations to clinically normal. When secreted in excessive quantities, hyperaldosteronism occurs.
Unlike in cats, hyperaldosteronism caused by a functional adrenocortical tumor is exceedingly rare in dogs. The most common presenting complaints in dogs with hyperaldosteronism are polyuria and weakness.3,4 The likely etiology for these clinical signs, hypokalemia, was identified on serum biochemical analyses for the dog of the present report and for all dogs in other reports.3,4 Diagnostic imaging, in particular ultrasonography, was useful in the present case and previous cases3,4 to evaluate for the presence of an adrenal mass. A definitive diagnosis is based on the finding of a high plasma aldosterone concentration, which in this case was demonstrated by an over 4-fold increase above the upper reference limit.
Unilateral adrenalectomy is the treatment of choice for clinically affected cats and dogs with hyperaldosteronism.3–5 However, in cases where surgery is declined or not viable due to metastatic disease, medical management can be pursued to address the hypokalemia. In the dog of the present report, evidence of extensive metastatic disease was identified in the liver and lung (not shown), thus surgery was not deemed fruitful. Instead, the dog was prescribed spironolactone and potassium gluconate to correct the hypokalemia. Unfortunately, the dog was lost to follow-up, thus the response to this treatment could not be assessed. Hyperaldosteronism, although rare in dogs, should be suspected when an adrenal mass and hypokalemia are present on clinical evaluation.
References
- 1. ↑
Pagani E, Tursi M, Lorenzi C, et al. Ultrasonographic features of adrenal gland lesions in dogs can aid in diagnosis. BMC Vet Res. 2016;12:267. doi:10.1186/s12917-016-0895-1
- 2. ↑
Cook AK, Spaulding KA, Edwards JF. Clinical findings in dogs with incidental adrenal gland lesions determined by ultrasonography: 151 cases (2007–2010). J Am Vet Med Assoc. 2014;244(10):1181–1185. doi:10.2460/javma.244.10.1181
- 3. ↑
Rijnberk A, Kooistra HS, van Vonderen IK, et al. Aldosteronoma in a dog with polyuria as the leading symptom. Domest Anim Endocrinol. 2001;20(3):227–240. doi:10.1016/s0739-7240(01)00090-x
- 4. ↑
Behrend EN, Weigand CM, Whitley EM, Refsal KR, Young DW, Kemppainen RJ. Corticosterone- and aldosterone-secreting adrenocortical tumor in a dog. J Am Vet Med Assoc. 2005;226(10):1662–1666. doi:10.2460/javma.2005.226.1662
- 5. ↑
Ash RA, Harvey AM, Tasker S. Primary hyperaldosteronism in the cat: a series of 13 cases. J Feline Med Surg. 2005;7(3):173–182. doi:10.1016/j.jfms.2004.08.007
