Autoimmune bullous skin disorders: Clinical

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Autoimmune bullous skin disorders: Clinical

USMLE® Step 2 questions

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USMLE® Step 2 style questions USMLE

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A 70-year-old man comes to the dermatology clinic because of a blister that was treated on his right upper arm two weeks ago. He has completed his course of clindamycin, as prescribed, with little to no improvement. During the last two weeks, a similar rash has appeared on his right forearm. He denies any travel, trauma, new hygiene products, or insect bites. He has had no fever or chills, gastrointestinal symptoms, joint pain, or numbness. Physical examination of his extremity reveals a large erythematous patch with clusters of bullae. There is no inguinal lymphadenopthy or mucosal involvement. Nikolsky sign is negative. Which of the following is the most appropriate treatment option for this patient at this time?


Autoimmune bullous disorders are a group of disorders in which the immune system mistakenly attacks the skin and mucosal membranes.

The lesions start as blisters, and then evolve into erosions, ulcers, and finally crusts. Often times this pattern occurs recurrently.

There are four main autoimmune bullous disorders - pemphigus, pemphigoid, dermatitis herpetiformis, and linear IgA bullous dermatosis.

Now for diagnosis, a history and physical can be followed up with a skin biopsy, serologic studies, and microbiologic tests.

A skin biopsy with light microscopy can reveal the skin layer involved in blister formation and the type of inflammatory cell infiltrate.

If it’s a small vesicle, then the entire lesion should be removed. For larger lesions, a specimen should be obtained from the edge of a blister, and it should contain both portions of the blister and intact skin.

Direct immunofluorescence studies are typically done when an autoimmune blistering disorder is suspected, because they can detect the antibody or complement deposition pattern and skin level of involvement.

For example, in pemphigus vulgaris and pemphigus foliaceus there’s intercellular antibody deposition in the epidermis, whereas in bullous pemphigoid there’s linear antibody deposition along the basement membrane.

Finally, it’s important to take a biopsy from normal-appearing skin adjacent to the blister, also called a perilesional biopsy, to get reliable results.

Also serologic testing may be useful for the evaluation of autoimmune blistering disorders, using indirect immunofluorescence to detect antibodies within the circulation.

If the target of circulating antibodies associated with specific autoimmune blistering diseases is known, antigen-specific testing can be used, such as ELISA, immunoblotting, and immunohistochemistry.

Let’s start off with pemphigus. Pemphigus includes a group of rare, but potentially life-threatening blistering disorders caused by autoantibodies that target adhesion molecules in the epidermis.


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