Dermatitis herpetiformis is a chronic disease that typically first appears in early adulthood. It is characterized by intense pruritus with alternate phases of activity and remission. Pruritic papules and vesicles develop preferentially and symmetrically on the buttocks and the extensor surfaces of the knees and elbows. Patients with dermatitis herpetiformis often have an associated gluten-sensitive enteropathy which may be asymptomatic. Iodine or iodides may be an enhancer or trigger for the disease.

Treatment

Patients usually require lifelong treatment; spontaneous remissions occur in about 10% of patients. A few patients respond adequately to a gluten-free diet alone, but most need indefinite treatment with dapsone. An initial dose of 100 mg daily usually suppresses the formation of new lesions within 24-48 hours and dramatically reduces pruritus. The dose may need to be increased to 200 mg daily. Administration of dapsone is associated with methaemoglobinaemia and haemolytic anaemia, particularly in patients with glucose-6-phosphate dehydrogenase deficiency. The dosage should then be reduced to the lowest dosage that will suppress symptoms.