Dermatopathology

Question 1

Summaries the Dermal reaction patterns

Answer 1

• Dermal fibrosis: increased collagenous connective tissue
• Fibrosis
  
  • desmoplasia/scirrhous response when induced by neoplasia (carcinomas, typically)
  • Fibroplasia: normal healing response
• Dermal atrophy: thinning of the dermal layer
  
  • hyperadrenocorticism, topical steroids, chronic ischemia, advanced age, starvation
• Dermal edema: perivascular or interstitial, can contribute to epidermal edema
• Dermal deposits: can presents as papules, nodules or plaques
  
  • Amyloid - plasmacytomas in dogs, hyperglobinemia, idiopathic
  • Calcium:
    
    • Calcinosis circumscripta: tumor-like growth composed of discrete calcium deposits surrounded by granulomatous inflammation; surgical removal curative
    • Calcinosis cutis: dermal calcium deposits associated the Cushings
  • Lipid:
    
    • Xanthomas - lipid deposits in the dermis that induce granulomatous inflammation; abnormal circulating lipids

Question 2

What is Ichthyosis?

Answer 2

• Heterogenous group of inherited, usually congenital alteration in epidermal cornification (stratum corneum) multiple species affected
• severe orthokeratotic hyperkeratosis
• Can be fatal (harlequin calf)

Question 3

What is Hereditary Zinc Deficiency?

Answer 3

• Abnormalities in zinc absorption and metabolism
• Parakeratotic hyperkeratosis
• Associated w/ thymic hypoplasia and diarrhea
• Autosomal recessive
• Lethal acrodermatitis of bull terriers: non-responsive to oral Zn supplementation
• Cattle- respond to oral Zn supplementation

Question 4

What is Epidermolysis bullosa

Answer 4

• Heterogenous group of diseases
• Cutaneous blister formation in response to minor mechanical trauma
• Poor dermal/epidermal cohesion
• Reported in horses, cattle, sheep, dogs, cats,
• Genetic mutation in structural proteins

Question 5

What is Aplasia cutis congenital (epitheliogenesis imperfecta)

Answer 5

• Distinct disease of swine
• Defect typically in caudal half of body
• Some piglets have hydroureter and hydronephrosis

Question 6

What is Congenital hypotrichosis?

Answer 6

• Partial or complete hair loss
• May be assocciated with other congenital abnormalities (brachygnathism, dental defects, thymic or genital abnormalities)
• Predisposes animals to sunburn, adverse reaction to extreme temperatures, bacterial/fungal infections

Question 7

What are the 2 types of Hypotrichosis associated with pigmentary alteration?

Answer 7

• Black hair follicular dysplasia
  
  • bi- or tri- colored black & white dogs
  • hair loss confined to pigmented areas
  • onset: weeks to months old
  • Rare hereditary disease
• Color-dilution alopecia
  
  • Slow progressive development
  • Onset 4 m to 3 y
  • Most common in blue doberman
  • relatively uncommon

Question 8

What is canine dermatomyositis?

Answer 8

• idiopathic inflammatory condition of skin, muscle, and occasionally blood vessels
• skin lesions usually develop in juvenile dogs at 7 weeks to 6 months
• Variability severity ad presentation with waxing/waning clinical signs
• Early skin lesions: pustules, vesicles, papules, nodules
• Skin lesions evolve into erythematous, crusty, ulcerated areas of alopecia w/ pigmentation abnormalities
• Histologic changes are variables subtle, and or non-specific

Question 9

What are the 2 categories of hereditary hypopigmentation?

Answer 9

• Melanocytopenic hypomelanosis (absences of melanocytes)
• Melanopenic hypomelanosis (melanocytes present but defective
  
  • Chediak-Higashi syndrome, cyclic hematopoiesis

Question 10

What is primary seborrhea

Answer 10

• Suspected inherited skin disease
• increased epithelial turnover without release of keratin
• Excessive scaling, crust, greasy coat
• Predisposed to skin infections (bacterial/fungi)
• Rule out other causes of seborrhea (acquired)

Question 11

What is acanthosis nigricans?

Answer 11

• Primary or idiopathic form occurs predominately in young dachshunds
• Bilaterally symmetric, axillary hyperpigmentation (subtle at first)
• Progresses to lichenification and alopecia

Question 12

What is collagen dysplasia

Answer 12

• group of inherited diseases; abnormal dermal collagen
• Enzyme defects of collagen synthesis
• Synonyms: Ehlers Danlos syndrome, cutaneous asthenia, dermatosparaxis
• Many species affected (including humans)
• Very loss, fragile skin

Question 13

What is Hereditary Equine Regional Dermal Asthenia (HERDA)?

Answer 13

• hyperelastosis cutis
• recessive inheritance
• very loose elastic skin
  
  • non-healing wounds
  • scarring