If your dermatologist suspects your itchy skin rash could be dermatitis herpetiformis, she'll almost certainly recommend a skin biopsy to confirm that diagnosis. Here's what to expect from the dermatitis herpetiformis skin biopsy and what that biopsy might show.
Dermatitis Herpetiformis Skin Biopsy Looks for IgA Under The Skin
When biopsying skin to determine if a rash is dermatitis herpetiformis, doctors look for deposits of Immunoglobulin A under the skin in a particular pattern. This distinctive granular IgA pattern is the hallmark of dermatitis herpetiformis.
To see these deposits, the physician must remove a sample of skin, stain it with a dye and examine it under a fluorescence microscope. If IgA deposits are present and in the correct pattern, then the person has dermatitis herpetiformis.
What To Expect From Your Dermatitis Herpetiformis Skin Biopsy Procedure
Dermatologists usually use what's called a "punch biopsy" to remove the skin and test it for dermatitis herpetiformis.
After injecting a local anesthetic, your dermatologist will use a tiny, cookie-cutter-like punch to remove a 4mm sample of skin. The incision can be closed with one stitch and generally heals with very little scarring.
It's important to have your dermatitis herpetiformis skin biopsy performed by someone who has diagnosed the skin condition before and knows how to do the biopsy. The skin sample must be taken from skin directly adjacent to the suspected dermatitis herpetiformis lesion, as opposed to directly from the lesion, since inflammation in the lesion can destroy the IgA deposits.
Treatment for Dermatitis Herpetiformis: The Gluten-Free Diet
If your biopsy comes out positive and you're diagnosed with dermatitis herpetiformis, your dermatologist may prescribe dapsone for short-term relief from the itching.
However, you'll need to follow the gluten-free diet to control your dermatitis herpetiformis long-term.
Dermatitis Herpetiformis. American Osteopathic College of Dermatology. Accessed Jan. 10, 2011.