Bullous Diseases Of The Skin

Question 1

Pemphigus (vulgaris or foliaceus)

Answer 1

Is an uncommon autoimmune blistering disorder that results from a loss of normal intercellular attachments within the dermis and squamous mucosal epithelium

3 major variants

• vulgaris (80%)
• Is by far the most common type and involves the mucosa and the skin layers of the scalp face, axilla, groin, trunk (oral ulcers often preceded however)

*lesions are painful, frequently develop secondary infections ANS require immunosuppressive therapy often for life.

• foliaceus
• Benign form that is endemic in Brazil and occurs sporadically in other geographic regions
• Common sites = scalp/face/chest/back, rarely on the mucus membranes
• is heavy associated with black fly bites in SA
• paraneoplastic

Question 2

Pathogenesis of pemphigus

Answer 2

Autoimmune IgG antibodies against demogleins
- disrupts intercellular adhesions direct IF shows “net-like” patterns of intercellular IgG deposit is

In vulgaris = seen at all levels
In foliaceus = superficial only

Question 3

What is the most common histological denominator in all forms of pemphigus

Answer 3

Acantholysis

- lysis of the intercellular adhesive junctions between neighboring squamous epithelial cells

Question 4

Bullous pemphigoid

Answer 4

Generally affects elderly individuals and is more common on the inner thighs and flexor surfaces

• 10-15% however are oral lesions
• • subset = gestational pemphigoid bullous which occurs in the 2nd-3rd trimester

Pathogenesis

• linear IgG autoantibodies in epidermal basement membrane
• also reactive Bullous pemphigoid antigen (BPAG) are attacked by autoantibodies

Clinical features

• dont rupture as easily as pemphigoid vulgaris and foliaceus. Also if they don’t rupture = wont scar
• treatment = immunosupression therapy and topical corticosteroids

Question 5

Dermatitis herpetiformis

Answer 5

Autoimmune blistering disorder associated with gluten hypersensitivity (Celiac disease)
- only a small amount of celiac patients develop dermatitis herpetiformis,however 80% of patients with this rash have celiac disease

Is more common in males and is extremely pruritic and is papulovesicle rash

• rash is bilateral and systemic and grouped
• more common extensor surfaces, elbows, knees, upper back and buttocks

Question 6

Dermatitis herpetiformis pathogenesis

Answer 6

Cross reactive IgA antibodies with endomysium and tissue transglutimanases especially in keratinocytes.

IF shows IgA granular deposits at the tips of dermal papillae

Question 7

Epidermolysis bullosa

Answer 7

Group of disorders caused by inherited defects in structural proteins
- leads to mechanical instability of the skin

Shows the tendency to from blisters at sites of pressure/trauma or excessive rubbing soon after birth

Question 8

Epidermolysis bullosa pathogenesis

Answer 8

Simplex type of EB

• caused by mutations in genes encoding keratin 5 or 14
• autosomal dominant mode of inheritance
• blisters are found in the basal cell layer of the epidermis
• includes 85% of epidermolysis bullosa

Junctional type of EB

• autosomal recessive defects in subunits of laminin proteins
• blisters develop at the lamina Lucinda

Scarring dystrophic types of EB

• blisters develop beneath the lamina densa in the anchoring fibrils
• caused by COL7A1 mutations that can be reccisve or dominant inheritance

Question 9

Porphyria

Answer 9

Group of uncommon inborn or acquired disturbances of porphyrin metabolism
- pigments are normally present in hemoglobin myoglobin and cytochromes

5 major types

1) CEP
2) EPP
3) AIP
4) PCT
5) MIxed porphyria

Cutaneous manifestations consist of urticaria and vesicles that scar and are exacerbated by exposure to sunlight