Abstract

We present a 76 year-old male with a 17 year history of dermatitis herpetiformis (DH) and celiac disease, who developed increasingly frequent and progressively extensive, intensely pruritic, red excoriated papules, despite strict adherence to gluten-free diet and dapsone. Examination revealed scattered, crusted erythematous papules on the trunk, gluteal cleft, and extensor extremities. Skin biopsy demonstrated a subepidermal cleft with numerous eosinophils on histopathology and linear IgG and IgG4 basement membrane zone (BMZ) deposition, as well as granular IgA papillary dermal deposition on direct immunofluorescence. Serological studies demonstrated circulating IgG autoantibodies with an epidermal pattern on primate salt-split skin substrate, positive BP180 and BP230 autoantibodies and negative IgA endomysial antibodies. The clinical presentation and histopathologic and immunopathological findings support a diagnosis of non-bullous pemphigoid developing in a patient with a known history of well-controlled DH, based on the absence of circulating anti-endomysial antibodies.

Cases of concurrent DH and bullous pemphigoid (BP) have been reported and a case-control study demonstrated a 22-fold increased risk of BP in patients with a diagnosis of DH, occurring at a mean interval of 3 years in this cohort. Epitope spreading, koebnerization and genetic predisposition are proposed mechanisms for this association.

This case highlights the development of BP in the context of long-standing DH and celiac disease under appropriate diet restriction and the importance of considering BP as a potential alternative cause of recalcitrant pruritic eruptions in DH patients.