Duhring's disease
Dermatitis herpetiformis is usually extremely itchy. The bumps or blisters usually appear on the elbows, knees, back, and buttocks. In most cases, the rash is the same size and shape on both sides. Symptoms of dermatitis herpetiformis tend to come and go.
A skin biopsy and direct immunofluorescence test of the skin are performed in most cases. Your doctor may also recommend a biopsy of the intestines.
Habif TP. Clinical Dermatology. 4th ed. St. Louis, Mo: Mosby; 2004.
McPherson RA, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. St. Louis, Mo: WB Saunders; 2006.