Immunoglobulins in the skin in dermatitis herpetiformis and their relevance in diagnosis.

Eighty skin biopsies from fifty patients with dermatitis herpetiformis (DH) have been examined for immunoglobulin deposits by direct immunofluorescence. IgA was found in all fifty patients. However, in two patients no IgA was detected in their first biopsy, and it is stressed that if the clinical suspicion of DH is high and no IgA is found in a single biopsy, then the biopsy should be repeated. There are two distinct patterns of immunoglobulin deposition in DH. The most common form of deposition is seen in the dermal papillae, termed the 'papillary' pattern. This pattern was the only one present in sixty-seven of the seventy-eight biopsies. A less common pattern is that of a 'continuous' line along the dermo-epidermal junction. This was the only pattern of immunoglobulin deposition in nine of the seventy-eight biopsies. In two biopsies both the papillary and continuous patterns were present. IgA was found in all seventy-eight of the positive biopsies and was the only immunoglobulin detected in sixty-seven biopsies. In addition to IgA, IgM was present in seven biopsies, and IgG in two biopsies. In one biopsy IgM and IgG were present with the IgA. The detection of IgA in the uninvolved skin in patients with DH is a simple test to perform, and at the present time is the most reliable way of establishing the diagnosis