Dermatitis Herpetiformis: Overview and Treatment Steps

Overview

Dermatitis herpetiformis is a chronic, intensely pruritic disorder characterized by symmetrically distributed bullae or erosions, deposition of IgA in the dermal papillae, and evidence of gluten-sensitive enteropathy. Only 10% of patients experience spontaneous remission. The therapeutic strategy is control of pruritus and at least most of the skin lesions.

First Steps

Following glucose-6-phosphate dehydrogenase (G6PD) screening, the drug of choice is dapsone 100 mg/day. Expect a dramatic clinical response within 4-5 days. Reevaluate the patient after 2 weeks, and increase dapsone to 200 mg/day if clinical improvement is inadequate. Check the complete blood count (CBC) every 2 weeks as the dose is increased.

Subsequent Steps

1. Continue the amount of dapsone required for clearing for 2 weeks, and then taper the drug by halving the dose every 2 weeks. Maintain the patient on the least amount of dapsone required for the control of lesions. Although most patients require between 50 and 150 mg daily, some patients are controlled on significantly lower doses (25 mg dapsone per week). Once the appropriate dapsone dose is found, the CBC is checked on a 6-month basis.

Alternative Steps

1. Sulfapyridine, supplied in 500-mg tablets, may be used in an initial dose of 1-2 g/day in patients who cannot tolerate dapsone. Taper to the minimum required dose is usually 1.0-1.5 g/day.
2. Combination therapy: If partial control is obtained on maximal doses of sulfapyridine (4 g/day), a small dose of colchicines may be added (0.6 mg once or twice daily).
3. Gluten-free diet: Because dermatitis herpetiformis is gluten dependent, most patients will respond to a gluten-free diet. The clinical response usually requires the patient to be on a rigid gluten-free diet for 6-12 months. Although not as ideal, even partial avoidance of gluten is helpful. To obtain dietary directions, refer the patient to a dietician skilled in treating patients with celiac disease. A successful dietary regimen requires an intelligent, highly motivated patient who dines at home. Most patients who adhere to their diet will be able to reduce their medication dose by 50% or more.

Complications and Undesired Consequences

1. The diagnosis of dermatitis herpetiformis should be re-evaluated in patients who do not respond to appropriately administered sulfone therapy. 
2. Screen patients prior to sulfone therapy for anemia and G6PD deficiency to avoid further anemia or severe drug-induced hemolysis. 
3. Follow the CBC at regular intervals in all patients during adjustment of sulfone dose. Once treatment dose is established, these tests and a white blood count need to be checked once or twice yearly. 
4. Patients with dermatitis herpetiformis are at increased risk to develop lymphoma of the GI tract. A gluten-free diet will prevent this complication. 
5. While a gluten-free diet takes 6 months to have efficacy and allows reduction or discontinuation of medication, gluten exposure may be followed within hours or days by a flare of the skin lesions.