Dermatitis herpetiformis and celiac disease are caused by an immune response to tissue transglutaminase, a component found in gluten. T-cells in the small intestine create a strong immune response and upregulate systemic cytokines and neutrophils. This proinflammatory environment allows immune system mediators to deposit in the skin, making the characteristic blistering skin lesions. In these disease processes, epidermal transglutaminase acts as the primary autoantigen. However, epidermal transglutaminase is a natural protein found in the body; it is recognized as foreign by the immune system. It is also thought that the IgA antibodies target the epidermal transglutaminases specific to DH. Researchers have hypothesized that these IgA-transglutaminase immune complexes then deposit in the skin. The blistering lesions closely resemble herpetic lesions, initially named “herpetiformis.” However, herpesviruses are not responsible for DH.
Dermatitis herpetiformis may be diagnosed by a healthcare professional through clinical findings, bloodwork, and skin biopsy. Blood tests can assess levels of IgA tissue transglutaminase antibodies, IgA epidermal transglutaminase antibodies, and IgA endomysial antibodies. Histology of a skin biopsy with light microscopy may show neutrophilic microabscesses at the dermal papillary tips. Direct immunofluorescence of the biopsy shows deposits of granular IgA at the dermal papillae, which is pathognomonic for DH.
DH is closely associated with celiac disease. If DH is suspected, a health care provider may also want to screen for celiac disease concurrently, which can be done through blood testing for IgA tissue transglutaminase, deamidated gliadin peptide, and anti-endomysial antibody. In addition, an endoscopy can be performed to biopsy the small intestine to assess for villous atrophy and crypt hyperplasia.Dermatitis herpetiformis may be treated with a combination of therapies. Adopting a lifelong gluten-free diet is essential in treating dermatitis herpetiformis and celiac disease. Examples of foods high in gluten include grains such as wheat, barley, and rye. Avoiding gluten can reduce the inflammatory response that causes both celiac disease and DH. Management of DH may involve an interdisciplinary team of dermatologists, gastroenterologists, and dieticians. They can develop personalized meal plans and help individuals understand which food groups to avoid.
It may take time, ranging from several months to years, for the rash to respond to a gluten-free diet. Therefore, in conjunction with a diet change, pharmacotherapy with dapsone, and an antibiotic, may be necessary. It is thought that dapsone exerts its effects through neutrophil function and recruitment. Dapsone use may be limited due to side effects, which include hemolysis, agranulocytosis (i.e., low immune system cells), and methemoglobinemia (i.e., a process by which hemoglobin becomes oxidized and cannot carry as much oxygen). A healthcare professional may taper Dapsone once the rash is under control. Refractory DH and flare-ups of the disease can occur in a small percentage of individuals who then require long-term dapsone treatment. In addition to these systemic options, topical steroids may be applied to reduce pruritus.Papadakis M, McPhee S, Rabow M. Current Medical Diagnosis and Treatment 2023. Mcgraw-Hill Education; 2022.
Saavedra AP, Roh EK, Anar Mikailov. Fitzpatrick’s Color Atlas and Synopsis of Clinical Dermatology, 9/E. McGraw Hill / Medical; 2023.
