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July 2007

Dog, Skin: Necrolytic Migratory Erythema

Detailed information.Animal: Dog, Cross Breed, 12 yr old, female, neutered.Organ: Haired Skin.

History: A 12 year-old, spayed female crossbred dog presented to a referral practitioner for a six week history of severe self trauma and licking of all four feet. Clinically there was erosion of the digital skin with erythema and severe hyperkeratosis of all digital pads (Figure 1). The dog was lethargic, anorexic and oligodipsic. On blood biochemistry, liver enzymes were elevated (alkaline phosphatase 1500 IU/l, alanine aminotransferase 563 IU/l) but blood glucose was within normal parameters. Ultrasound examination of the liver revealed multiple, diffuse nodules throughout the liver, as well as distended hepatic vasculature. Following biopsy of the digits, further erosive lesions developed in areas of the lips. The dog deteriorated rapidly and the dog was subsequently euthanised on humane grounds.

Histological findings: All sections of skin there was marked diffuse compact parakeratosis, marked oedema of the stratum spinosum/granulosum and the basal and supra-basal keratinocytes were moderately, diffusely, hyperplastic (French flag appearance).

Necropy Findings: Pathological alterations were confined to the liver which was of reduced size with multinodular and pitted surfaces. Nodules varied from 2mm to 40mm and on cutting of the liver were present throughout the parenchyma and involved all lobes. Histologically sections of liver tissue revealed marked disruption of lobular architecture. There were multiple, variably sized nodular organisations of swollen hepatocytes which displayed sinusoidal arrangement but were lacking normal portal triads. Within the connective tissue in areas of parenchymal collapse, multiple small bile ducts, swollen hepatocytes displaying cytoplasmic vacuolation as well as prominent multiple veins and arteries were present.

Diagnosis: Dog, Skin: Necrolytic Migratory Erythema with moderate superficial pyoderma.

Comment: Necrolytic migratory erythema (NME) is a skin eruption first reported in humans with alpha cell pancreatic tumours and elevated plasma glucagon concentrations (i.e., glucagonoma syndrome). A small number of humans with NME do not have a glucagon-secreting tumour. In the veterinary literature, superficial necrolytic dermatitis (SND) (metabolic epidermal necrosis (MEN)) is an uncommon necrotising skin disorder of dogs (and rarely cats) associated with incompletely characterised hepatic disease. .The vast majority of dogs do not have a demonstrable glucagonoma and instead have a hepatopathy with characteristic histopathological and ultrasonographic features (i.e., hepatocutaneous syndrome). Although the exact pathophysiological mechanisms are not known, hypoaminoacidaemia appears to be a consistent finding, suggesting there is underlying cutaneous nutritional deprivation.

Histopathological findings are usually consistent but the classical ‘French flag’ (see above) appearance is not always identified from skin biopsies especially when lesions are relatively chronic. Dogs usually have erosive and ulcerative lesions, with exudation, alopecia and crusting surrounding the pawpads and around the mucocutaneous junctions of the lips, eyes, clawbeds and anus.Other lesions can arise at other sites usually involving pressure points. Biopsy sites should include erythematous plaques with mild to moderate adherent crusts avoiding areas of ulceration.

Histological findings from liver tissue consist of severe hydropic and ballooning degeneration. Areas of severe parenchymal collapse result in consolidation of the reticulin fibre network. Foci of nodular hepatocyte regeneration are prominent which can be confused with hepatic cirrhosis. Long term survival of canine patients is limited and treatment is usually palliative. The cause of the degenerative hepatopathy is not known.

Photo by: Richard Fox