Blistering Dermatosis Flashcards
What is a “blister?”
Occurs when the epidermis separates from the basement membrane of the dermis, or when the different layers of the epidermis separates from one another, creating a space filled with fluid called “blister.”
What is the disease when there is autoimmune destruction of the desmosomes? What is happening in this disease?
“Pemphigus Vulgaris.” IgG antibodies against the “desmoglein.”
What can be seen in the immunofluoresence of Pemphigus Vulgaris?
Will show “fish net” where the IgG will surround the keratinocytes.
What is “desmoglein?”
It is a component of the desmosomes, and desmosomes are what holds the stratum spinosum cells together.
What is the classic histological finding of Pemphigus Vulgaris?
The Basal layer will be fine, and the epidermal layer will also be fine, however in between the two there will be a blister due to the destruction of desmoglein (part of desmosomes) which was supposed to hold the stratum spinosum together.
What is “acantholysis?” Where does acantholysis present in pemphigus vulgaris?
Seperation of the keratinocytes. Somewhat opposite of “acanthosis” which is thickening of the keratinocytes. Appears in the stratum spinosum in pemphigus vulgaris.
How are basal cells attached to the basement membranes? How do they appear in pemphigus vulgaris?
Attached via hemidesmosomes. The basement membrane will appear as “Tombstones.”
Besides the skin, what else can pemphigus vulgaris involve?
It can also involve the oral mucosa.
How does the epidermis in pemphigus vulgaris compare with normal? What is the consequence of this?
Relatively thin epidermis not containing all of the layers, resulting in a thin walled blister that can easily rupture making shallow erosions with dried crust on the skin.
What is the disease caused when there is an autoimmune destruction of the hemidesmosomes?
Bullous Pemphigoid.
What is happening pathology wise in Bullous Pemphigoid?
IgG antibodies against the BM, autoimmune attack.
How would Bullous Pemphigoid present clinically?
Subepidermal blisters of the skin, however unlike pemphigus vulgaris, the oral mucosa is spared in this case.
How does the Bullae of Bullous Pemphigoid compare with Pemphigus Vulgaris
Pemphigus Vulgaris have easy to rupture blisters, in contrast the blisters in Bullous Pemphigoid is tense and do not rupture easily.
Where does the blister in Bullous Pemphigoid form and why?
Since the IgG abs are targeted against the hemidesmosomes which hold the basal layer together, there will be an entire dissociation between the dermis and epidermis, causing a blister to form in between these two layers.
How would the IF look for Bullous Pemphigoid?
A linear IF will be seen.
Why is the blister formed by the bullous pemphigoid hard to rupture as compared to pemphigoid vulgaris?
The entire epidermis is involved in bullous pemphigoid hence tougher to rupture, whereas in pemphigus vulgaris the epidermis only has a few, not all, of its layers.
What disease process presents as autoimmune IgA deposition at the tips of dermal papillae?
Dermatitis Herpetiformis. IgA will be deposited at the tips of the papillae of dermis where the blood vessels is supposed to feed the epidermis. A blister forms at the tips, giving the appearance of the blisters one would see in herpes.
How does dermatitis Hepetiformis present and what is it strongly associated with?
Strongly associated with Celiac’s disease, it presents as itchy vesicles and bullae that are grouped.
Why is the IgA being formed in Dermititis herpetiformis amd why the association with celiac’s?
There is an autoimmune attack against gluten (Celiac’s disease) that cross react with reticulin fibers that attach the basement membrane to dermis
How would dermatitis herpetiformis be treated?
Same way you would treat celiac’s disease, dietary control of gluten which will lead to decreased IgA formation against gluten.
What disease process is caused by a hyper sensitivity reaction that leads to a “targetoid rash with bullae?”
Erythema Multiforme.
What is a common association of Erythema Multiforme?
HSV infection, but also with mycoplasma, some drugs like PCN, autoimmune diseases like SLE and with malignancy.
What gives the “targetoid appearance” of Erythema Multiforme?
Red erethamatous and circular rashes will form with a white center due to necrosis of the center, giving it the target like appearance.
How is Erythema Multiforme related to Steven Johnson Syndrome and Toxic Epidermal Necrolysis?
The rashes of EM + fever + oral mucosa involvement = Steven Johnson Syndrome. Severe form of SJS is called Toxic Epidermal Necrolysis TEN.
How would TEN present and what generally causes it?
Diffuse sloughing of the skin resembling a large burn is how it would present and this is usually due to an AE of a drug. Medical Emergency.
