Hepatocutaneous syndrome/superficial necrolytic dermatitis (SND) in dogs
Amanda Mansz
Animal Health Laboratory, University of Guelph, Guelph, ON
AHL Newsletter 2023;27(4):22.
A 9-year-old male Shiba Inu presented to the AHL for postmortem with a history of chronic hepatic disease. On external examination, the dog was very thin with generalized mild icterus of the skin and mucous membranes. Multiple roughly symmetrical, large regions of alopecia were situated on the hind end (around the tail, hips and caudal aspect of the thighs), the ventral abdomen and thorax, and the muzzle (Fig. 1A). Affected skin appeared wet/exudative or crusted, thickened and flakey. All paw pads were diffusely and markedly hyperkeratotic (Fig. 1B). Internally, the liver was very small and had a generalized “cobblestone” appearance of the capsular surface. There was bridging and coalescing fibrosis intersecting between variably-sized nodules of hepatocellular hyperplasia (Fig. 1C).
Microscopic review of the liver confirmed the marked hepatic fibrosis and parenchymal collapse with multinodular hepatocellular regeneration. Hepatocellular vacuolation, portal vascular and biliary proliferation, and cholestasis were also present (Fig. 2B). Sections of affected skin showed the classic “red, white, and blue” pattern of superficial necrolytic dermatitis (SND) characterized by a thick overlaying parakeratotic hyperkeratosis (red), ballooning degeneration, epithelial necrolysis and spongiosis of the underlaying layers of epithelium (white), and a deeply basophilic hyperplastic epithelial basal layer (blue) (Fig. 2A).
In dogs, hepatocutaneous syndrome or SND is a rare, chronic, and progressive syndrome most commonly associated with severe liver disease, such as severe vacuolar hepatopathy, idiopathic hepatocellular collapse, and hepatopathy secondary to anti-convulsant drug administration. More rarely, it can accompany cases of glucagonoma and gastric carcinoma.
Classic skin lesions consist of roughly bilaterally symmetrical, erythematous erosive to ulcerative and crusted lesions of the muzzle, lips, periocular skin, edges of the pinnae, distal extremities, ventrum, points of pressure or friction, and the external genitalia. Oral and mucocutaneous lesions are occasionally reported. The footpads are markedly hyperkeratotic.
This condition is very rarely reported in cats without the associated footpad hyperkeratosis. A similar syndrome has been described in horses with erosive, ulcerative, and exudative coronitis and concurrent liver pathology.
The pathogenesis of SND is unknown, but hepatic dysfunction and derangement of glucose and amino acid metabolism are thought to be implicated, most likely involving abnormal or impaired ability to properly use nutrients.
Figure 1. Canine hepatocutaneous syndrome. A. Alopecia with erosive, ulcerative, and crusted lesions of the muzzle. B. Marked footpad hyperkeratosis. C. Microhepatica with severe hepatic fibrosis, parenchymal collapse and multinodular hepatocellular regeneration
Figure 2. Canine hepatocutaneous syndrome. H&E stains. A. Footpad skin with the classic “red, white and blue” lesions of superficial necrolytic dermatitis. Thick parakeratotic hyperkeratosis (red arrow), ballooning degeneration, epithelial necrolysis and spongiosis of the epithelium (white arrow), and the hyperplastic epithelial basal layer (blue arrow). H&E stain, 2x. B. Severe bridging hepatic fibrosis and parenchymal collapse (white arrow) with multinodular hepatocellular regeneration (red arrow). H&E stain, 2x.
References
1. Cullen JM, Stalker MJ. Liver and Biliary System. In: Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals, 6th ed. Maxie MG, ed. Elsevier, 2016;vol 2:295.
2. Mauldin EA, Peters-Kennedy J. Integumentary System. In: Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals, 6th ed. Maxie MG, ed. Elsevier, 2016;vol 1:586.