Two Japanese cases of dermatitis herpetiformis associated each with lung cancer and autoimmune pancreatitis but showing no intestinal symptom or circulating immunoglobulin A antibodies to any known antigens.

Dermatitis herpetiformis (DH) is common in some Caucasian populations but extremely rare in Japanese, probably because of different immunogenetic backgrounds. We report two Japanese DH cases with typical clinical, histological and direct immunofluorescence features. However, no symptom of gluten-sensitive enteropathy was shown. The diagnosis was confirmed by eliminating other autoimmune blistering diseases by indirect immunofluorescence, enzyme-linked immunosorbent assays and immunoblotting. However, circulating immunoglobulin (Ig)A anti-endomysium, reticulin and gliadin antibodies were not detected. IgA antibodies to tissue and epidermal transglutaminases were also negative. One case was associated with lung cancer and the other one with autoimmune pancreatitis. On review of 17 cases of DH reported in Japan over the previous 10 years, including our cases, one case was associated with gluten-sensitive enteropathy, four with malignant neoplasms, two with autoimmune systemic disorders and one with psoriasis. Although our cases were typical of DH in clinical, histopathological and IgA deposit features, they showed different human leukocyte antigen haplotypes, no gluten-sensitive enteropathy and no DH-specific IgA antibodies, including those to epidermal and tissue transglutaminases. These results suggest that studies of unique characteristics in Japanese DH patients should facilitate further understanding of pathogenesis in DH.