Skin Other - Pathology

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()Map INTEGUMENTARY SYSTEM (Map)



Epidermal growth or differentiation disorders

Seborrheic disease complex

  • Abnormal cornification or function of sebaceous glands
  • Large amounts of free fatty acids and cholesterol
  • Decreased amounts of diester waxes in surface lipids
  • Bacterial population changes to pathogenic coagulase positive staphylococci
  • Chronic disease affecting mainly dogs, sometimes cats and horses
  • Dry form - white to grey scales
  • Greasy form - scaly, excess brown to yellow lipids sticking to skin and hair

Primary idiopathic seborrhea

  • Abnormal cornification
  • Epidermal turnover reduced to about 2/3 of normal
  • Microscopically:
    • Hyperkeratosis distending follicular ostia causing papillary appearance
    • Parakeratosis at edges of follicular ostia
    • Congested, oedematous dermal papillae
    • Spongiotic epidermis with leukocytes

Secondary seborrhea

  • Develops secondarily to many types of disease (e.g. ectoparasites, fungal infections, endocrine disease, internal disease or allergy)
  • Microscopically:
    • Hyperkeratosis and/or parakeratosis of follicles and epidermis
    • Lesions relevant to the other disease

Sebaceous adenitis

  • Inflammation of sebaceous glands, alopecia, hyperkeratosis
  • Possibly immune-mediated
  • Mainly affects dogs
    • Long haired show multifocal, serpiginous and annular lesions
  • Microscopically:
    • Inflammation of sebaceous glands
    • Possibly orthokeratotic hyperkeratosis
    • Chronic lesions are deprived of sebaceous glands and contain mild inflammation and fibrosis at follicular isthmus

Pigmentation disorders

Hypopigmentation

Hyperpigmentation

Eosinophilic infiltration

Eosinophilic plaques

Eosinophilic granulomas

Eosinophilic folliculitis and furunculosis

Sterile granulomatous disorders

Juvenile pyoderma

Equine generalised granulomatous disease