A case of dermatitis herpetiformis with IgA endomysial antibodies but negative direct immunofluorescent findings

A patient with clinical findings of dermatitis herpetiformis (DH), negative direct immunofluorescent (DIF) findings for junctional IgA deposits in 2 b iopsy specimens, and positive For IgA endomysial (AEmA) and tissue transglu taminase (tTG) antibodies responded initially to dapsone. After dapsone had to be discontinued because of side effects, a gluten-free diet and support ive therapy controlled the disease; the AEmA and tTG antibodies became nega tive. Our data on 10 consecutive DH cases examined by DIF and by serum stud ies for AEmA and antibodies to tTG, point to frequencies of 90% DIF positiv e and 70% AEmA. and tTG positive cases. The use of both DIF and serum tests for AEmA and tTG reveals DH cases not detected by DIF alone that respond t o gluten-free diet. Findings on autoantibodies to tTG, an enzyme that metab olizes gliadin, points to a role of tTG in the immunopathology of gluten-se nsitive enteropathy and helps to explain the need for a gluten-free diet in the management of DH cases.