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DERMATITIS HERPETIFORMIS

DERMATOLOGY LECTURE NOTES

DEBABRATA BANDYOPADHYAY
PROFESSOR & HEAD, DEPT. OF DERMATOLOGY,
R. G. KAR MEDICAL COLLEGE, CALCUTTA, INDIA

 

 

Dermatitis herpetiformis (DH) or Duhring's disease, is a chronic, intensely itchy, symmetrical polymorphic rash consisting of papules, vesicles, and bullae typically located on extensor surfaces. DH is associated with gluten sensitive enteropathy in almost all cases. Autoantibody to transglutaminase is responsible for this subepidermal blistering disorder.
 

 

ETIOLOGY & PATHOGENESIS

 
  • Gluten sensitive enteropathy is responsible in some way to the development of IgA autoantibodies to transglutaminase.
  • Deposition of circulating epidermal transglutaminase-IgA autoantibody complex at the dermal papillary tips activates complement by the alternative pathway. Ensuing neutrophil accumulation and liberation of proteases leads to destruction of dermal papillary tissue, separation of epidermis from dermis, and cleft formation.
  • Genetic influence is evident by frequent association of HLAs B8, DR3, and DQw3.
  • Lesions of DH may be precipitated by administrations of iodides and gluten-rich diet.

CLINICAL FEATURES

 

  • Dermatitis herpetiformis is rare in Asians and Africans.

  • Both sexes are affected equally, some reported slight male preponderance.

  • Average age of onset is between 20 to 40 years, childhood onset may also occur. Age and sex incidence may vary between populations.

  • Lesions are erythematous papules, urticaria-like plaques, vesicles, and bullae. Grouping of blisters is characteristic. Blisters are usually tense.

  • Intense itching, often paroxysmal, and burning sensation are predominant symptoms. Excoriated lesions with crusted erosions occur due to scratching.

  • Distribution is typically symmetrical, on the extensor surfaces: elbows, shin, knee, scapular region, lumbo-sacral region, buttock, scalp, hairline.

  • Mucosal lesions may occur.

  • Healing of lesions may leave hyper- or hypopigmented spots.
     

  • Associated features/complications:
         
    Thyroid disorders: hypo-, and hyperthyroidism, thyroid nodules, cancer.
          GI conditions: gluten enteropathy, usually subclinical; gastric atrophy.
          Intestinal lymphoma: can be prevented by gluten-free diet
          Autoimmune diseases: Type 1 diabetes, myasthenia gravis,
                                         dermatomyositis, SLE,

 

DIFFERENTIAL DIAGNOSIS

  • Bullous pemphigoid
  • Erythema multiforme
  • Papular urticaria
  • Insect bite
  • Atopic dermatitis
  • Contact dermatitis
  • Scabies
  • Linear IgA disease
  • Grover's disease (transient acantholytic dermatosis)
 

DIAGNOSIS

 
 
  • Typical clinical features of extremely pruritic, grouped papulovesicular lesions with excoriations, symmetrically distributed on the extensors, is highly suggestive.

  • Histology: Erythematous skin adjacent to an early blister should be biopsied. Accumulation of neutrophils and eosinophils at the tip of dermal papillae  with formation of microabscesses. Separation develops between dermal papilla and the overlying epidermis. These clefts coalesce at places to develop subepidermal bullae.

  •  Direct immunofluorescence: The biopsy should be taken from clinically normal skin. It shows granular deposit of IgA in dermal papilla.  Dapsone therapy doesn’t alter direct immunofluorescence  finding, but prolonged adherence to gluten free diet results in disappearance of the deposits.

  • Indirect immunofluorescence: Autoantibody to smooth muscle endomysium is found in a large number of cases.
    Other autoantibodies that may be detected are: thyroid microsomal antibodies, antinuclear antibodies, and anti-reticulin antibodies.

 
 

COURSE AND PROGNOSIS

 
 
  • Untreated, dermatitis herpetiformis generally runs a life-long course with  intermittent exacerbation and  remission.
  • Spontaneous permanent remission may occur in some patients.
  • General health of the patients, however, is not affected by the disease.

 

 
 

TREATMENT

 
 
  • Drugs: Dapsone is the drug of choice. Usually started at 100mg/day, the dose may be increased to 400mg/day depending on response. After remission, the dose is reduced and the minimum dose effective for prevention of relapse is continued. Careful monitoring for side-effects like hemolytic anemia, methemoglobulinemia, and neutropenia should be done. Sulphapyridine (1.5 g/day) is an alternative.
     

  • Diet: For long-term remission, gluten-free diet should be advised. This takes a long time to take effect. Wheat, barley, and rye are the dietary constituents that contain gluten. Although extremely difficult for most patients to adhere to, a gluten-free diet eventually may make withdrawal of dapsone possible. Gluten-free diet also diminishes the chance of developing lymphomas.        

 
 

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