Dermatitis herpetiformis

Microscopic Image of Dermatitis Herpetiformis

Dermatitis herpetiformis is characterised by an intensely itchy, chronic, papulovesicular eruption, usually on elbows, knees and buttocks.

The diagnosis is based on granular IgA deposits in the dermal papillae in a perilesional skin biopsy analysed by immunofluorescence microscopy.

Most patients have subclinical celiac disease; a gluten-free diet is effective in most cases.

Microscopic features:

Early lesions: Collections of neutrophils and varying number of eosinophils. These are located at the tips of edematous dermal papillae (papillary microabscesses).

In lesions of 36-48 hours duration: There is increase in the number of eosinophils. There may be fragmentation of neutrophils.

In older lesions: There is evidence of subepidermal vesicle formation. Vesicles contain neutrophils, eosinophils and fibrin. Occasional shadow epidermal cells may be present.

The histological distinction between dermatitis herpetiformis and linear IgA bullous dermatosis is almost impossible.

Vist: Vesiculobullous Reaction Pattern

The imbalance between metalloproteinases and their tissue inhibitors is involved in the pathogenesis of dermatitis herpetiformis. Mediators Inflamm. 2005 Dec 14;2005(6):373-9.

Dermatitis herpetiformis (DH) is a subepidermal autoimmune disease characterized by skin and intestinal lesions consistent with coeliac disease. There are also some data that metalloproteinases (MMPs) are involved in the development of skin lesions in DH, however their exact role in this process is not fully understood. The aim of the study was to investigate whether MMPs and their inhibitors are involved in pathogenesis of DH. Skin biopsies were taken from 13 patients with active DH and from 10 healthy subjects. The localization and expression of MMPs and TIMPs were examined by immunohistochemistry. MMPs expression was detected in basal keratinocytes and in the whole epidermis in all of the DH subjects. Neutrophils in microabscesses and in blister fluid were also positive for MMPs. Expression of TIMPs was moderate or weak in all examined biopsies. Our results allow us to conclude that imbalance between these enzymes takes an important role in the pathogenesis of DH.

Subepidermal blistering disorders: a clinical and histopathologic review.Semin Cutan Med Surg. 2004 Mar;23(1):10-8.

The subepidermal blistering disorders are comprised of a number of unrelated disorders with a diverse clinical presentation and pathogenic basis that share in common the presence of blister formation beneath the epidermis. Many of the disorders are both debilitating and potentially fatal. Timely and accurate diagnosis facilitates their appropriate management. The etiologic, clinical, and pathologic attributes as well as the treatment of these disorders including bullous pemphigoid, epidermolysis bullosa acquisita, dermatitis herpetiformis, linear IgA dermatosis, cicatricial pemphigold, herpes gestationis,and porphyria cutanea tarda are described.

Dermatitis herpetiformis.Dermatol Online J. 2003 Oct;9(4):8.

Dermatitis herpetiformis is a chronic, lifelong disease characterized both by symptomatic, characteristic skin lesions and by a gluten-sensitive, often asymptomatic, enteropathy. Cutaneous findings include intensely pruritic vesicles on symmetrical extensor locations. Treatment for disease may be pharmacologic agents or a gluten-free diet. Evidence for the genetic basis of disease has been elucidated.

Dermatitis herpetiformis.Baillieres Clin Gastroenterol. 1995 Jun;9(2):371-93

Dermatitis herpetiformis (DH) is a relatively rare skin disorder with an estimated incidence of 1:10,000 in the UK. It is characterized by urticarial plaques and blisters on the elbows, buttocks, and knees, although other sites may also be involved. The eruption tends to be persistent: only 10-15% of patients have spontaneous remission over a 25-year study period. The disease is characterized by the presence of IgA deposits in the upper dermis of uninvolved skin and the diagnosis should not be made in the absence of these deposits. Two-thirds of patients have a small intestinal enteropathy with villous atrophy as seen in coeliac disease (CD). However, the remaining third also show evidence of a gluten sensitivity in the intestine, as judged by increased lymphocytic infiltration of the epithelium. Villous atrophy also ensues after gluten challenge in those patients with previous normal villous architecture. The initial treatment of the rash is with one of the following three drugs, dapsone, sulphapyridine or sulphamethoxypyridazine. However, the rash also clears with gluten withdrawal. It must be stressed, however, that the average time to achieve significant reduction in drug requirements is 6 months and it can be over 2 years before drugs are no longer required. On re-introduction of gluten the eruption recurs. Patients with DH have a high incidence of auto-immune disorders, thyroid disease, pernicious anaemia, and insulin-dependent diabetes, and should be screened for those diseases on a yearly basis. As with coeliac disease there is also an increased incidence of lymphoma and a gluten-free diet appears to protect patients from this complication. The mechanism by which gluten causes the skin lesions has still to be elucidated, but current investigations implicate lymphocytes and cytokines in the pathogenesis. The original hypothesis of an antigen-antibody reaction in the skin with complement activation causing the skin lesions, may not be correct.