Autoimmune Skin Disorders

1.  Pemphigus vulgaris:

• IgG autoantibody is formed and attaches to desmogleins 1, 3 (this causes the cement holding the cells together to break down)
• The mouth is usually the first to be affected (the patient will complain of difficulty swallowing) then later comes the skin involvement
• Characteristics:
  • Multiple slow healing shallow erosions in the oral mucosa and on upper trunk
  • Acantholytic intraepidermal blistering  (remember that acantholysis is when the keratinocytes are separated from one another)
  • Nikolsky sign:  lateral surface pressure cause epidermal shearing from the dermis (Dr. Schwartz will never test us on the specific names of the signs but I would know the characteristic)

2.  Pemphigus Foliaceus

• IgG autobodies attack desmoglein 1 of the granular layer
• Look like superificial erosions
• Endemic form in Brazil
• Characteristics
  • More superficial than the common form
  • Oral involvement is usually not seen
  • When viewed histologically, the epidermal separation is higher

3.  Bullous Phemphigoid

• Causes:
  • circulating IgG and C3 bind to dermal epidermal junction
  • IgG autoantibodies bind to hemidesmosomal BP Ag BP230 and BP180 (or BPAg1 and Ag2)
• Characteristics:
  • Seen a lot in nursing home populations
  • Will start on the extremities and then spread everywhere
  • Takes the form of tense bullae on the skin
  • Most concerned with secondary infections and death due to sepsis

4. Collagen Vascular Disorders     

      1.  Systemic Lupus Erythematosus

·         Three forms:  acute, subacute and chronic forms

·         Characteristics: 

o        Photodermatitis: commonly on the trunk but also a “wolf” butterfly rash can occur across the face

o        In systemic disease there can also be serositis, arthritis, pancytopenia, anemia and thrombocytopenia

o        Anti-dsDNA is found in acute SLE (present in 60-80% in high titers)

o        Anti-Sm antibody also can have a strong specificity for SLE and is a very valuable sign when there isn’t a presence of anti-dsDNA

·         Lupus Band test:  to see if there are IgG, IgM, IgA and complement components found at the dermal epidermal junction   (60% of people with LE with have a positive Lupus Band test).  If a patient has nonlesional skin and a positive band test it correlates strongly with aggressive SLE

2.  Discoid Lupus Erythematosus

·         Involves the skin

·         DLE will sometimes occur along with SLE and can actually develop into SLE in about 5% of patients

·         Characteristics

o        Chronic scarring, atrophy producing photosensitive dermatosis

o        Presence of calmine covered plaques with scaling

o        Follicular plugging

o        Can resemble regular eczema so you have to be careful to diagnose

·         These patients can’t go in the sun and if they do they have to wear long sleeves, wear a hat or carry an umbrella

·         20% of patients will have positive ANA (the anti-dsDNA Ab) with human substrates 

3.  Dermatomyositis

·         Characteristics:

o        Photodermatitis with periorbital heliotrope (looks like rings around the eyes)

o        Gottran papules on knuckles:  red bumps

o        Proximal muscle weakness (patients will complain they can’t do things like open the garage door)

·         Mimics LE histologically and clinically but you are less likely to find ANA

·         There is an increased risk of occult cancers in adults 

4.  Scleroderma:

·         Progressive systemic sclerosis

·         Characteristics:

o        Crest syndrome:  Calcification, Raynaud’s disease, esophageal dysfunction, sclerodactyly, telangectasia (looks like skin damage)

o        Skin is very tense so you have unlined forehead, beaked nose, radial perioral furrowing

o        Claw hand 

5.  Localized scleroderma

·         Morphea

·         More common in children and young adults

·         Characteristics:

o        Firm white patch or violaceous patch (depigemented skin)

o        Muscle and bone involvement is very rare but can occur

o        The patient can have facial hemiatrophy wher half their face is involved (coup de sabre or saber wound)

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