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Dermatology and Musculoskeletal > Blistering diseases - Levin > Flashcards

Blistering diseases - Levin Flashcards

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1
Q

By definition, what is a blister?

In the skin, where do blisters occurr

Name the types of blisters

A

A blister is a seperation between layers of the skin

Intraepidermal - between the layers of the epidermis

Subepidermal - beneath the epidermis

Vesicle - a blister less than 1cm

Bulla - a blister greater than 1cm

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2
Q

What holds the skin together?

A

Desmosomes - connect adjacent keratinocytes in the epidermis

Hemidesmosomes - connect cells in the basal layer to the basement membrane

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3
Q

What are the types of blistering disorders?

A

Genetic - Epidermolysis bullosa caused by mutations in basal layer keratins and hemidesmosomal proteins

Infectious - Staphylococcal scalded skin syndrome, bullous cellulitis, Herpes simplex virus, Varicella zoster virus

Traumatic/physical causes - Friction blister, coma bulla, burns (including sunburn), cryotherapy

External contactants - Contact dermatitis (poison ivy), chemical burns, vesicants (e.g. blister beetle juice)

Drug reaction - Stevens Johnson Syndrome, Toxic Epidermal Necrolyis

Metabolic - Porphyria cutanea tarda

Autoimmune Disease - Pemphigus vulgaris, pemphigus foliaceus, bullous pemphigoid, dermatitis herpetiformis, linear IgA bullous dermatosis

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4
Q

What are the classifications of the blister by the level of the skin

A

Subcorneal: Subcorneal pustular dermatosis of Sneddon and Wilkinson

Granular layer: Staphylococcal scalded skin syndrome

Upper spinous layer: Pemphigus foliaceus

Spinous layer: Friction blister

Lower spinous layer: Pemphigus vulgaris

Basal layer: Epidermolysis bullosa simplex

Subepidermal: Bullous pemphigoid, dermatitis herpetiformis, linear IgA bullous dermatosis, epidermolysis bullosa acquisita, junctional and dystrophic epidermolysis bullosa

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5
Q

Staphylococcal scalded skin sydrome

Who does it usually affect

what is the typical history of patients with this syndrome

A

Staph positive on culture

May precede respiratory infection

Prodrome of malaise, fever, irritability and very tender skin

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6
Q

What is the clinical presentation of Staphylococcal Scalded Skin Syndrome?

A
  • Rapid course: Erythema spreads from head to entire body within hours; develops wrinkled appearance within a day and then sloughs, leaving behind moist denuded skin and crust
  • Over 3-5 days, scaling and desquamation occurs
  • Spares palms, soles and mucous membranes
  • After 1-2 weeks healing occurs w/o scarring
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7
Q

What is the pathophysiology of Staphylococcal Scalded Skin sydrome?

A
  • Staphylococcus aureus at distant focus (nose, pharynx, ear, umbilicus)
  • Blisters are sterile (unlike bullous impetigo)
  • Epidermolytic toxins A and B; produced by Group II S. aureus Phages (types 3A, 3C, 55, 71)
  • Toxins cleave Desmoglein 1, a desmosomal protein in the upper spinous layer, leading to an intra-epidermal blister
  • Toxins cleared by the kidneys (neonates, adults with renal failure have poor clearance)
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8
Q

The differential for staphylococcal scalded skin syndrome includes:

A

Toxic epidermal necrolysis

Kawasaki’s disease

Viral exanthem

Toxic shock syndrome

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9
Q

What is Nikolsky’s sign and in what diseaes is it seen?

A

It is seen in Staphylococcal scalded skin sydrome - and it is when lateral pressure on unblistered skin induces a new blister (skin peels off)

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10
Q

What is Asboe-Hansen’s sign and in what disease is it seen?

A

It is seen in Staphylococcus Scalded Skin Syndrome - it is when pressure on top of a blister causes it to extend into normal appearing skin

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11
Q

What is the pathology seen in Staphylococcal Scalded Skin Syndrome?

A

Oral treatment with a beta-lactamase resistant penicillin or cephalosporin antibiotic for 1 week is usually sufficient

Apply bland emollients to skin

Isolate patient from other infants to prevent spread of Staph.

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12
Q

What is the treatment of Staphylococcal Scalded Skin Syndrome?

A
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13
Q

What are the three main types of Pemphigus?

What causes pemphigus

A

Pemphigus vulgaris (can be severe)

Pemphigus foliaceus (milder one)

Paraneoplastic pemphigus (can be severe)

Pemphigus is caused by lack of cohesion between keratinocytes (acantholysis) and mediated by IgG antibodies to desmosomal proteins

Rare and often fatal

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14
Q

Which group of people is mostly affected by pempigus vulgaris?

A

Adults 5th (40s) and 6th decade (50s)

Jewish and Mediterranean descent

HLA DR4, DR6 DQ1

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15
Q

What are the clinical features of pemphigus vulgaris

A

Classic - development of oral and other mucous membrane erosions

Most also develop large, flaccid bullae arising from normal apprearing skin, contain clear to hemorrhagic fluid; rapidly rupture to form erosion/crusts

The bullae may begin in mouth; groin, scalp, face, neck, axillae, genital area

Nikolsky’s sign positive

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16
Q

What is the pathology of Pemphigus vulgaris?

A

Acontholysis - dissociation of keratinocytes

Acontholysis is at the suprabasilar level - its an intraepidermal blister

Non-inflammatory

Only the basal cell layer remains at the floor of the blister “row of tombstones”

17
Q

Explain the differences in indirect and direct immunoflourescence in pemphigus vulgaris

A
  • Direct IF
    • Fluorescently labelled Abs to IgG are applied to patient’s skin biopsy specimen
    • These Abs detect presence of patient’s IgG deposits within their own epidermis directed against DSG-3 and often DSG-1
    • Intercellular staining throughout epidermis appears as a “chicken wire fence”
  • Indirect IF:
    • patient’s serum containing IgG to desmoglein- 3 (and often DSG-1) is applied to an epithelial substrate such as monkey esophagus
    • Circulating IgG levels correlate with disease activity
18
Q

What is the treatment for Pemphigus vulgaris?

A

Systemic corticosteroids (prednisone)

Steroid sparing agents: azathioprine, cyclophosphamide, mycophenolate mofetil

Plasmapheresis, Intravenous immunoglobulin G (IVIG)

Rituximab: an anti-CD20 monoclonal antibody that decreases pathogenic IgG production

19
Q

Which group of people get Pemphigus foliaceus

A

Adults, 40-50 years

An endemic type occurs in Brazil

20
Q

What is the clinical presentation of pemphigus foliaceus?

A

Small flaccid bullae, rupture as soon as they appear; crusting and bleeding

Scal, face and trunk affected

Mucosal lesion are NOT a feaure (different from p. vulgaris)

Evolves into localized or generalized exfoliation; burning pruritis

Nikolsky’s sign is present

This is the milder form of pemphigus

21
Q

What is the pathology of pemphigus foliaceus

A

Acantholysis in upper epidermis, granular layer

Subcorneal blister

22
Q

Immunoflourescence in pempigus foliaceus

A

Direct IF: intercellular IgG in upper epidermis

ELISA: Antibodies to Desmoglein 1, NOT Desmoglein 3

Contrast to Pemphigus vulgaris: Abs to DSG-3 +/- DSG-1

23
Q

What are the antibody profiles in pemphigus

Pemphigus foliaceus?

Pemphigus vulgaris (oral lesions only)

Pemphigus vulgaris (oral and skin lesions)

A

Pemphigus foliaceus - Demoglein 1

Pemphigus vulgaris (oral lesions only) - Desmoglein 3

Pemphigus vulgaris (oral and skin lesions) - Desmoglein 1 and 3

24
Q

What is the treatment of pemphigus foliaceus?

A

Treatment is the same as pemphigus vulgaris:

Systemic corticosteroids (prednisone) - However topical steroid can also be used since this is a milder disease

Steroid sparing agents: azathioprine, cyclophosphamide, mycophenolate mofetil

Plasmapheresis, Intravenous immunoglobulin G (IVIG)

Rituximab: an anti-CD20 monoclonal antibody that decreases pathogenic IgG production

25
Q

What is bullous pemphigoid - pathophysiology

A

It is an autoimmune subepidermal blistering disease involving autoantibodies to hemidesmosomal proteins

More common and better prognosis than pempigus vulgaris

It is associated with HLA class II DQB1*0301 in Caucasians

26
Q

Who is most likely to have bullous pemphigoid?

A

Its most common in the elderly

27
Q

What is the clinical presentation of bullous pemphigoid?

A

Generalized symmetric intensely pruritic eruption with widespread tense blisters (unlike pemphigus which has flaccid blisters)

Early stage may be urticarial (hives) or eczematous, rather than bullous

Lower legs, thighs, groin area, flexor surfaces of forearms

20-30% have mucosal involvement

Does not scar

Nikolsky’s sign negative

Often self-limited (5-6 year period); may come and go for years

Typically not life threatening

28
Q

What is the pathology of Bullous pemphigoid

A

Subepidermal split

Inflammatory blister cavity with eosinophils

29
Q

Bullous Pemphigoid immunostaining

A

DIRECT IMMUNOFLUORESCENCE

  • LINEAR STAINING for IgG and C3 along basement membrane zone

INDIRECT IMMUNOFLUORESCENCE

  • 70% have circulating IgG
  • Level does not correlate with disease activity (IN CONTRAST TO PEMPHIGUS)
30
Q

What are the bullous pemphigoid antigens?

A

Bullous pemphigoid antigen 1 is a 230 kD protein in the hemidesmosomal plaque

Bullous pemphigoid antigen 2 is a 180 kD protein, also called type XVII collagen, that makes up anchoring filaments

31
Q

How do you treat bullous pemphigoid

A

TREATMENT: Suppress inflammation; wait for remission (unlike pemphigus)

  • Oral and topical steroids
  • Tetracycline/niacinamide
  • Immunosuppressive agents (azathioprine, mycophenolate moffetil)
32
Q

Who is mostly affected by dermatitis herpitiformis?

A

Most common in Northern Europeans

Usual onset at 20-40 years old

33
Q

What is the clinical presentation of dermatitis herpitiformis?

A

An intensely pruritic subepidermal blistering disease associated with gluten sensitivity (celiac disease) and IgA Abs against tissue transglutaminase

  • >90% have gluten-sensitive enteropathy on small bowel biopsy
  • 20% are symptomatic with celiac disease
  • Increased risk of intestinal lymphoma (3%) and thyroid disease

Associated with HLA DQ2A1*05B1*02

Clinical presentation:

  • Symmetrical, grouped vesicles (often excoriated) on extensor surfaces, scalp, neck, posterior axillary folds, buttocks
  • No mucous membrane involvement
  • Intense burning and itching
  • Nikolsky’s sign negative
34
Q

What is the pathogenesis of dermatitis herpitiformis?

What are the histological features?

A

Antigenic stimulation by gluten leads to inflammation and IgA antibodies

IgA Abs bind to epidermal transglutaminase and form IgA-immune complexes that are deposited in skin

Complement activated inflammation leads to neutrophils in dermal papillae

Histology:

  • Subepidermal vesicles
  • Neutrophils in groups at the dermal papillae +/- eosinophils
35
Q

Where should immunoflourescence be taken

What do you see?

A

Direct IF should be taken from peri-lesional skin

IgA in a granular pattern at the dermal papillae

36
Q

How do you treat dermatitis herpetiformis

A

Dapsone: Its an antineutrophilic agent. Highly effective

Gluten-free diet alone can cause remission, though this may take months to years; reduces risk of intestinal lymphoma

37
Q

Epidermolysis bullosa

What is it?

What are the types?

A

A group of inherited blistering disorders

Three main types:

  • Simplex: Split occurs in basal cell layer –> Keratins 5 and 14 defect (intermediate filament proteins expressed in basal layer)
  • Junctional: Split within basement membrane zone –> laminin 5; alpha-6, beta-4 integrins; type XVII collagen defects
  • Dystrophic: Split beneath basement membrane –> type VII collagen defect
38
Q

Epidermolysis bullosa

Clinical presentation

Treatment

A

Clinical presentations - vary widely from very mild localized variants EM simplex (Weber-Cockayne) to universally fatal generalized types (Herlitz Junctional type)

There is also a recessive dystrophic type - it has a risk of sqaumous cell carcinoma (usually cause of death)

Treatment is largely supportive and consists of specialized dressings and wound care

Future treatments: gene therapy?

Dermatology and Musculoskeletal (10 decks)

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