Dermatitis herpetiformis: an evaluation of diagnostic criteria

Forty-two patients in whom a clinical diagnosis of dermatitis herpetiformis (DH) had been, made, were studied. All patients had a small intestinal biopsy, a biopsy of uninvolved skin for detection of the presence of IgA deposits by immunofluorescence, serum and red cell folate estimations and examination of the serum for anti-reticulin antibody. The response of the skin eruption to dapsone was noted. Thirty patients had biopsies of skin lesions for routine histological examination. IgA deposits were found in the uninvolved skin of thirty-five of the forty-two patients. Evidence of an enteropathy was found in thirty-four of those thirty-five patients. Of the seven patients who did not have IgA in the uninvolved skin, only one showed evidence of enteropathy, which was slight, and this patient was shown subsequently to have pemphigus and not DH. Of the thirty biopsies of skin lesions, only five showed all the features usually considered to be characteristic of DH. And-reticulin antibody was found in eight patients, and in all of these IgA was present in the uninvolved skin. Low red cell folate levels were found in eleven patients (all of whom had an enteropathy and IgA in the uninvolved skin). Low serum folate levels were found in thirty-four patients, thirty-one of whom had IgA deposits in the uninvolved skin and an enteropathy; in the other three patients who did not have IgA deposits or an enteropathy, all were on dapsone and this may have accounted for the abnormal result. In forty-one of the forty-two patients the rash was dapsone responsive. The patient who showed no response to dapsone had no IgA in the uninvolved skin and no evidence of enteropathy. Follow-up showed that of the seven patients with no IgA in the skin, one had pemphigus, and in three the rash eventually cleared spontaneously and the patients no longer required treatment. There was no evidence of spontaneous remissions in the patients with IgA in the uninvolvcd skin. It would appear that the presence of IgA deposits in the uninvolved skin is part of the syndrome of DH and that the diagnosis should not be made unless these deposits are found.