Dermatitis herpetiformis

Dermatitis herpetiformis (DH), or Duhring's Disease,^[1][2] is a chronic blistering skin condition,^[3] characterised by blisters filled with a watery fluid.^[4] Despite its name, DH is not related to or caused by herpes virus: the name means that it is a skin inflammation having an appearance similar to herpes.

DH was first described by Dr. Louis Duhring in 1884.^[5] A connection between DH and gluten intolerance (coeliac disease) was recognised in 1967,^[5][6] although the exact causal mechanism is not known.

The age of onset is usually about 15-40, but DH can also affect children and the elderly. Men and women are equally affected. Estimates of DH prevalence vary from 1 in 10000 to 1 in 400.^{[7][8][9][10]}

Symptoms

Dermatitis herpetiformis is characterized by intensely itchy, chronic papulovesicular eruptions, usually distributed symmetrically on extensor surfaces (buttocks, back of neck, scalp, elbows, knees, back).^{[8][11][1]:616} The blisters vary in size from very small up to 1 cm across.

The condition is extremely itchy, and the desire to scratch can be overwhelming.^[12] This sometimes leading to the blisters being scratched off before they are examined by a doctor.^[8] Intense itching or burning sensations are sometimes felt before the blisters appear in a particular area.^[13][4]

Untreated, the severity of DH can vary significantly over time, probably in response to the amount of gluten ingested.^[13]

Diagnosis

Diagnosis is confirmed by a simple blood test for IgA antibodies,^[14] and by a skin biopsy in which the pattern of IgA deposits in the dermal papillae, revealed by direct immunofluorescence, distinguishes it from linear IgA bullous dermatosis^[8] and other forms of dermatitis. These tests should be done before the patient starts on a gluten-free diet, otherwise they might produce false negatives. If the patient has already started a gluten-free diet, it might be necessary for them to come off it for some weeks before the tests can be done reliably.

Treatment

Dermatitis herpetiformis responds well to medication and changes in diet.

Dapsone is an effective treatment for most patients. DH responds to dapsone so quickly (itching is significantly reduced within 2-3 days^[12]) that this response may almost be considered diagnostic. However, dapsone treatment has no effect on any intestinal damage (see coeliac disease) that might be present.^[10]

A strict gluten-free diet must therefore also be followed,^[14] and this will usually be a lifelong requirement. This will reduce any associated intestinal damage,^[14][12] and the risk of other complications. After some time on a gluten-free diet, the dosage of dapsone can usually be reduced or even stopped,^[12] although this can take up to anything from 1 to 3 years.

Dapsone is an antibacterial, and its role in the treatment of DH, which is not caused by bacteria, is poorly understood. It can cause adverse effects on the blood, and regular blood monitoring is required.^[4]

Dapsone is the drug of choice, but for patients unable to tolerate dapsone for any reason, the following can be tried, although they are less effective:

• colchicine
• lymecycline
• nicotinamide
• tetracycline^[4]
• sulfamethoxypyridine
• sulfapyridine^[4][14]

Complications

DH is an autoimmune disease, and patients with DH are more likely than others to have thyroid problems^[14][8] and intestinal lymphoma.^[9][11][8]

Notable cases

It has been suggested that French revolutionary Jean-Paul Marat suffered from DH,^[15] leading him to spend much of his time in, and even work from, a bathtub filled with an herbal mixture that he used to calm the sores.

References

See also

• Coeliac disease
• Gluten-free diet

External links

• Pictures: Elbow Arms
• Pictures: DermNet NZ
• Pictures: The Gastrolab Image Library
• Pictures: mediscan
• DermNet immune/dermatitis-herpetiformis

• A collection of articles from Celiac.com
• Journal of Investigative Dermatology
• Medline Plus