OSCE Scenario - The Bullous knee

[doctor_b]

A 25 year old lady is referred to you by her GP, to whom she presented with several large "blisters" on her knees (see image).



What is the differential diagnosis of bullae?

Spoiler for Answer:

Bullous erythema multiforme, TEN, dermatitis herpetiformis, porphyria, renal disease, diabetes, carbon monoxide toxicity, barbituate use, pemphigus vulgaris, bullous pemphigoid and epidermolysis bullosa

What is pemphigus vulgaris?

Spoiler for Answer:

The most dramatic and serious of the family of pemphigus diseases; it is a chronic, life-threatening autoimmune bullous disease of mucous membranes and skin, with defective adhesion of epidermal cells.

What is it's incidence and risk factors?

Spoiler for Answer:

PV is uncommon and occurs at any age. Jewish or Mediterranean ethnicity afford a higher risk

What is its appearance?Where does it start? What is its distribution?

Spoiler for Answer:

Flaccid blisters that break easily and become weeping erosions. It starts on mucous membranes in more than 50% of cases, a distinctive feature which helps in diagnosis. It may remain localised to the mucous membranes or spread to the scalp, face, chest, axilla or groin.

What is Asboe-Hansen's sign?

Spoiler for Answer:

The ability to extend a PV blister by pressing on the lateral edge.

What is the Nikolsky's sign?

Spoiler for Answer:

Creation of new pemphigus vulgaris blisters by pressing on uninvolved skin

How is diagnosis made?

Spoiler for Answer:

Skin biopsy. Histology reveals a suprabasilar blister and immunoflorescence shows intracellular IgG

What is the treatment for pemphigus vulgaris?

Spoiler for Answer:

Systemic steroids, azathioprine and cyclophosphamide

What is the prognosis for pemphigus vulgaris?

Spoiler for Answer:

Fatal if untreated and 10% mortality rate with treatment. Exacerbations and remissions occur

[cute_angina]

This is a cool review! I was reading Annals of Emergency Med last month and when I saw the picture of pemphigus in their Images section, I thought

• "Whoa! that is a seriously painful looking rash" and
• How come I've never heard of this disease?

I've attached the picture in a pdf for your to "ooh and aah" over!

[nimamd]

Thanks! very interesting!

[medman]

thanks...so nice