Small Animal Dermatology, 3rd edition

CHAPTER 45 SUPERFICIAL NECROLYTIC DERMATITIS 667

 Toxic epidermal necrolysis

 Cats: exfoliative dermatitis (thymoma associated), pancreatic paraneoplastic alope-

cia, epitheliotropic lymphoma, erythema multiforme, pemphigus foliaceus, FeLV- and

FIV-associated dermatoses

DIAGNOSTICS

 CBC: inconsistent findings: microcytosis (40–67%), low PCV, monocytosis, throm-

bocytosis.

 Biochemistries:
Hepatic: elevated serum alkaline phosphatase, alanine aminotransferase, aspar-

tate aminotransferase

Hyperglycemia

Elevated total bilirubin and bile acids

Hypoalbuminemia variable.

 Elevated plasma glucagon levels: consistently noted with glucagon-secreting pancre-

atic or extrapancreatic neoplasia; rarely observed with hepatopathy.

 Hypoaminoacidemia: notably glutamine, proline, cysteine, hydroxyproline.

 Urinalysis: rare ammonium biurate crystalluria; aminoaciduria – notably lysinuria,

prolinuria.

 Abdominal ultrasound:
Pathogonomic “honeycomb” or “Swiss cheese” hepatic appearance
Variably sized, hypoechoic regions measuring 0.5–1.5 cm in diameter sur-

rounded by highly echogenic borders

Hypoechoic regions correspond to distinct regenerative nodules (nodular hyper-

plasia) bounded by regions of severe parenchymal collapse.

 Lesions lack extensive fibrosis and reduced liver size usually associated with chronic

cirrhosis.

 Rare pancreatic or extrapancreatic neoplasia (Figures 45.6, 45.7).

 Dermatohistopathology:
Distinctive “red/white/blue” pattern:
Parakeratosis and neutrophilic crusting
Pallor of epidermis above the basal layer due to intracellular and
intercellular edema
Hyperplastic basal cell layer
Clefting within the epidermis
Mild neutrophilic superficial to perivascular dermal infiltrate
Marked parakeratosis with absence of epidermal pallor noted in chronic cases.

 Hepatic histopathology:
Vacuolar hepatopathy (not seen with pancreatic tumor)
Hepatocyte degeneration
Parenchymal collapse
Nodular hyperplasia.