Difference between revisions of "Skin Other - Pathology"

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===Hyperpigmentation===
 
===Hyperpigmentation===
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*Results from irritation or inflammation, pigmented [[Skin Neoplastic - Pathology|neoplasms] or [[Endocrine effects on the skin|metabolic diseases]]
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*Lentigo - circumscribed macular or slightly raised plaque with epidermal hyperplasia and hyperpigmentation
  
 
==Eosinophilic infiltration==
 
==Eosinophilic infiltration==

Revision as of 12:03, 31 October 2008



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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

  • Leukoderma or vitiligo - loss of pigment in the skin
  • Leukotrichia - loss of pigment of the hair
  • Hypopigmentation or incomplete albinism - generalised reduction of pigment in skin or hair
  • Albinism - inherited lack of pigment
  • Dilution - reduced pigmentation
  • Can be localised or generalised, idiopathic or asociated with other diseases
  • Examples of hereditary conditions: Maltese dilution of cats, Chediak-Higashi syndrome, leukoderma and leukotrichia of Dobermans, Arabian fading syndrome
  • Asociated with some immune-mediated disorders, e.g. discoid lupus erythematosus

Hyperpigmentation

  • Results from irritation or inflammation, pigmented [[Skin Neoplastic - Pathology|neoplasms] or metabolic diseases
  • Lentigo - circumscribed macular or slightly raised plaque with epidermal hyperplasia and hyperpigmentation

Eosinophilic infiltration

Eosinophilic plaques

Eosinophilic granulomas

Eosinophilic folliculitis and furunculosis

Sterile granulomatous disorders

Juvenile pyoderma

Equine generalised granulomatous disease