Chapter 32 - Dermatitis Herpetiformis and Linear IgA Bullous Dermatosis Flashcards
What is the eponym associated with dermatitis herpetiformis?
Duhring’s disease
True or false: the majority of patients with dermatitis herpetiformis are aware of having gluten sensitivity.
False; although virtually every patient with dermatitis herpetiformis has celiac disease, only 20% have intestinal symptoms, and thus patients tend to be unaware of their gluten sensitivity
How can linear IgA bullous dermatosis be distinguished from dermatitis herpetiformis on DIF?
Linear IgA bullous dermatosis will show linear IgA along the basement membrane, while dermatitis herpetiformis will show granular deposition of IgA within the dermal papillae
True or false: the first-line therapy for the treatment of dermatitis herpetiformis, and the associated intestinal disease, is dapsone.
False; dapsone is considered first-line for the skin, but the intestinal disease will not respond at all to dapsone
True or false: DH is more common in African-Americans and Asians than people of northern European origin.
False; DH occurs most commonly in people of northern European origin and it’s uncommon in African-Americans and Asians
True or false: men get DH more often than women.
True; men outnumber women two to one
Which HLA type is most closely associated with DH?
90% of patients have HLA-DQ2, and the remaining patients have HLA-DQ8
Use the “BROW” mnemonic to list the grains that contain gliadin, the alcohol-soluble fraction of gluten that is believed to be the antigen in celiac disease.
Barley, rye, oats, and wheat (oats don’t technically contain gliaden, although they’re usually produced in facilities that also produce wheat, contaminating them)
What is the specific target antigen found in the skin of patients with DH?
Epidermal transglutaminase
What is the hallmark of DH on DIF?
Granular deposition of IgA in the dermal papillae
Consumption of which non-metal element is known to dramtically worsen DH?
Iodine (found ubiquitously, but in highest concentrations in seafood and seaweed)
Which two autoimmune diseases are most closely associated with DH?
Thyroid disease (especially Hashimoto’s thyroiditis) and DM1
Which specific type of thyroid disease is most commonly associated with DH?
Hashimoto’s thyroiditis
Does adhering to a gluten-free diet for patients with DH protect against the development of gut lymphoma?
Yes (well, it reduces the risk anyways)
True or false: isolated scalp involvement is one way DH can present.
True
Where should a biopsy of DH be taken for H&E? What about DIF?
- Small intact vesicle for H&E
- Perilesional skin for DIF
If no intact vesicle can be found in a patient with DH for H&E, where should the biopsy be taken from?
An area of erythema
On H&E of DH, subepidermal blisters will be seen filled with inflammatory cells. Which inflammatory cells are most frequently present?
Neutrophils (although sometimes eosinophils are seen)
True or false: eosinophils are sometimes present in biopsies of DH, so on H&E, bullous pemphigoid, linear IgA bullous dermatosis, and bullous SLE cannot be distinguished.
True
True or false: antiendomysial antibodies are very specific for celiac disease and DH.
True
Can antiendomysial antibody levels be used to determine a patient’s compliance to dietary gluten restriction?
Yes
What is “endomysium”?
Endomysium is the connective tissue cover of the smooth muscle layer of gut; anti-endomysial antibodies are very specific for celiac disease and DH
What is the specific endomysial antigen that has been identified in celiac disease and DH?
Tissue transglutaminase
How quickly does the pruritus associated with DH subside after starting dapsone?
Within 48-72 hours