Clinical Features

Superficial Necrolytic Dermatitis

•glucagonoma is a rare endocrine tumor of the α pancreatic cells and has been reported in 8 dogs

•glucagonoma is associated with a characteristic dermatitis of the footpads = superficial necrolytic dermatitis

•synonyms: metabolic epidermal necrosis, necrolytic migratory erythema, and diabetic dermatitis

•skin lesions can also occur on the muzzle, mucocutaneous junctions, elbow, hocks, pinnae, and external genitalia

•skin lesions tend to wax and wane and can be pruritic with secondary bacterial infections

•however, superficial necrolytic dermatitis is not pathognomonic for glucagonoma as 78 cases of superficial necrolytic dermatitis have been reported and only 7 of these were diagnosed with concurrent glucagonoma

•classification scheme has been proposed: superficial necrolytic dermatitis, superficial necrolytic dermatitis and hepatocutaneous syndrome, and suspected superficial necrolytic dermatitis, with glucagonoma reported in:

•9% of dogs with superficial necrolytic dermatitis

•60% of dogs with superficial necrolytic dermatitis and hepatocutaneous syndrome

•31% of dogs with suspected superficial necrolytic dermatitis

•superficial necrolytic dermatitis resolves following successful surgical resection of the pancreatic glucagonoma

•DDx: pemphigus foliaceus, SLE, generic dog food dermatosis, and zinc-responsive dermatosis

From: Withrow SJ & MacEwen EG (eds): Small Animal Clinical Oncology (3rd ed).

Diabetes Mellitus

•glucagon promotes gluconeogenesis and glycogenolysis

•hyperglycemia will result if there is an excess of glucagon relative to insulin

•diabetes mellitus will occur if insulin production cannot match the excessive secretion of glucagon

Other Clinical Signs

•other clinical signs include weight loss, polyuria, and polydipsia

•weight loss is caused by the catabolic effects of glucagon on fat and protein metabolism

Diagnosis

•hematologic and serum biochemical abnormalities include non-regenerative anemia and elevated liver enzymes ± hypoalbuminemia, decreased BUN, and persistent hyperglycemia

•skin biopsy: diffuse parakeratotic hyperkeratosis with high levels of confluent vacuolation of keratinocytes resulting in epidermal edema, with minimal dermal changes (i.e., perivascular accumulation of lymphocytes and plasma cells)

•chronic lesions may have superficial to lichenoid inflammatory infiltrates

•abdominal and thoracic imaging for detection of a pancreatic mass and metastatic disease

•however, pancreatic mass was only detected in 13% (1/8) dogs with ultrasonographic examination

•multiple diffuse hypoechogenic foci in the liver (= honeycomb pattern) is present in 50% (4/8) dogs with glucagonoma and is consistent with hepatic metastases

•plasma glucagon levels in the absence of hypoglycemia strongly supports the diagnosis of glucagonoma

Treatment

•exploratory celiotomy with partial pancreatectomy and clinical staging for metastatic disease

•tumor debulking can decrease the intensity of skin lesions in humans with glucagonoma

•octreotide is recommended for medical management of humans with glucagonoma

•other medical treatment options include decarbazine and streptozotocin with 5-fluoroucil

Prognosis

•prognosis is poor with metastasis common and widespread at diagnosis

•survival times range from 3 days to 9 months