Skin Pathology: Bullous Disorders

Question 1

What characterizes bullous disorders from other skin dermatoses? What are the major disorders of this category?

Answer 1

• these disorders have blisters (vesicles, bullae) as their primary feature (many other disorders also have blisters, but not as the main characteristic)
• major bullous disorders: pemphigus vulgaris, bullous pemphigoid, dermatitis herpetiformis

Question 2

What is a blister?

Answer 2

• a blister is a fluid-filled bubble within the skin that occurs due to the separation of a layer within the skin
• small blisters are called vesicles, larger ones are called bullae

Question 3

What is pemphigus vulgaris? Where do the bullae form? Can it affect the mucosa?

Answer 3

• pemphigus vulgaris is an uncommon bullous disorder due to autoimmune destruction of desmosome proteins in the epidermis (usually the stratum spinosum)
• bullae form between the basal cells and the rest of the epidermis (these are intraepidermal blisters); they are thin walled and flaccid, and prone to rupturing; they are painful
• IF reveals a “fish net” pattern of deposited IgG surrounding the keratinocytes
• pemphigus vulgaris can affect both the skin and the oral mucosa
• (don’t get confused with bullous pemphigoid!)

Question 4

What is bullous pemphigoid? Where do the bullae form? Can it affect the mucosa?

Answer 4

• bullous pemphigoid is a bullous disorder due to autoimmune destruction of hemidesmosome proteins in the basement membrane
• bullae form below the basement membrane, in the dermis (subepidermal blisters); they are thick walled and tense, difficult to rupture
• bullous pemphigoid ONLY affects the skin, not the mucosa
• (don’t get confused with pemphigus vulgaris!)

Question 5

What is pemphigus foliaceus? How does it differ from pemphigus vulgaris?

Answer 5

• pemphigus foliaceus is another form of pemphigus, but is even less common than pemphigus vulgaris
• the bullae here also form in the intraepidermal area, but are more superficial, forming just under the corneum (subcorneal blisters)
• bullae in pemphigus vulgaris are supra basal (which are also intraepidermal)

Question 6

What is dermatitis herpetiformis? What is it highly associated with?

Answer 6

• dermatitis herpetiformis is an autoimmune bullous disorder characterized by extremely pruritic urticaria (hives) and groups of vesicles (resembles herpes, hence the name)
• 80% of cases are associated with celiac disease! (these cases actually also resolve with a gluten free diet)
• the disorder is due to IgA deposits in the tips of the dermal papillae (these IgA antibodies are the anti-gluten antibodies found in celiac disease); subepidermal blisters result