Derm Path 1 ()

• Portion of the skin that contains:

  - Hair follicles

  - Sebaceous glands

  - Apocrine glands

  
  

  Adnexa is embedded in the dermis.


  What is the adnexa? Where is it found?

  
• Basement membrane (BM)


  Which layer of the epidermis provides the scaffold for migrating keratinocytes during wound healing?
• Heals by scarring


  What kind of healing occurs if the basement membrane of the epidermis is damaged?
• Stratum basale


  Which layer of the epidermis houses stem cells for keratinocyte proliferation?
• Terminal differentiation of keratinocytes


  What is cornification?
• Shedding of cornified keratinocytes (corneocytes)


  What is desquamation?
• 22 days


  How long does migration of skin cells from the stratum basale to stratum corneum take? (Essentially, how long does it take for complete skin turnover?
• Langerhans cells


  Which cells in the epidermis are antigen-presenting cells with immune-surveillance functions?
• Merkel cells


  Which cells in the epidermis serve as mechanoreceptors?
• Collagen


  What substance provides strength in the dermis?
• - Intracellular edema (hydropic degeneration)

  - Intercellular edema (spongiosis)

  - Keratinocyte apoptosis or necrosis


  What are the outcomes for acute epidermal injury?
• - Epidermal hyperplasia

  - Epidermal and follicular hyperkeratosis

  - Hyperpigmentation

  
  

  Grossly, this looks like thickening and crusting.


  What are the outcomes of chronic epidermal injury?
• Dermal edema


  What is the outcome of acute dermal injury?
• - Dermal fibrosis

  - Dermal atrophy


  What are the outcomes of chronic dermal injury?
• Congenital = lesions present at birth

  
  

  Hereditary = inherited (genetic); lesions may be congenital or develop later in life


  What is the difference between a "hereditary" or "congenital" disease (how to the definitions differ)?
• Identify the histologic lesion and the cause of the condition seen in the photo.

  The histologic feature of ichthyosis ("fish scales") is orthokeratotic hyperkeratosis, as seen here


  
• Identify the histologic lesion and the cause of the condition seen in the photo.

  diffuse parakeratotic hyperkeratosis,the histologic lesion for hereditaryzinc deficiency

  
• Lethal acrodermatitis (hereditary zinc deficiency)

  
  

  Seen in bull terriers


  Based on the signalment, name a top Ddx

  
• False - need histo!


  True or false: ichthyosis and zinc deficiency can be distinguished based on gross appearance

  
• Golden retrievers


  Which breed is predisposed to mild ichthyosis on the trunk?
• Cattle


  In which species do we see ichthymosis fetalis, a fatal form of the disease?
• In cattle: condition responds to oral zinc supplementation

  
  

  In bull terriers: the condition does NOT respond to oral zinc supplementation and the condition is lethal


  Compare and contrast the outcomes of hereditary zinc deficiency in cattle vs. bull terriers
• Minor mechanical trauma results in blistering and ulceration of the skin


  What is the primary feature of epidermolysis bullosa (formerly called epitheliogenesis imperfecta)?
• Aplasia cutis congenita (previously called epitheliogensis imperfecta)


  What is pictured here?

  
• Aplasia cutis congenita occurs with no trauma. There is simply skin missing when the animal is born. Rare condition seen in pigs.

  
  

  Epidermolysis bullosa becomes apparent after some sort of minor trauma. This is mostly reported in horses (belgian and saddlebred).


  What is the difference between epidermolysis bullosa and aplasia cutis congenita?
• Albanism is a hereditary hypopigmentation in which melanocytes are present but have defective melanin synthesis


  Describe the pathogenesis for albinism
• What is the pathogenesis for vitiligo?

  
  

  Vitiligo is a type of hereditary hypopigmentation caused by melanocytopenic hypomelanosis, which is the absence, loss, or destruction of melanocytes.


  *note: this is different from albinism in which melanocytes ARE present
• Artic breeds such as:

  - Akita

  - Samoyed

  - Husky

  - Malamute


  What is the common signalment for uveodermatologic syndrome?
• - Bilateral panuveitis

  - Bilateral cutaneous depigmentation of the lips, nose, periorbital skin


  What are the clinical signs for uveodermatologic syndrome?

  
• Seborrhea means "flow of sebum" and it is a clinical term to describe "excessive scaling"


  What is seborrhea?
• False - it is a clinical description


  True or false: Seborrhea is a histologic diagnosis
• Dry scale (seborrhea sicca) or oily/greasy scale (seborrhea oleosa)


  What clinical appearance is associated with seborrhea?
• Abnormal collagen causes:

  - Loose and variably fragile skin

  - Skin may be torn

  - May have joint laxity


  What are the clinical lesions associated with collagen dysplasia in any species?

  
• Compare and contrast dermatosis vegetans and porcine juvenile pustular psoriasiform dermatitis.

  Dermatosis vegetans:

  - Inherited disorder of Landrace pigs

  - Thick crusts surrounded by red raised border

  - Lungs also affected (giant cell pneumonia)

  - FATAL

  
  

  Porcine juvenile pustular psoriasiform dermatitis:

  - Landrace pigs may be predisposed?

  - Thick crusts surrounded by red raised border

  - Spontaneous resolution in about 4 weeks

  
• - Dermatosis vegetans

  - Porcine juvenile pustular psoriasiform dermatitis


  Give two DDx for this case