Dermatitis Herpetiformis

1. See Also
   1. Bullous Disease
2. Epidemiology
   1. Incidence: Up to 39 cases per 100,000
   2. Usual onset at 20 to 40 years
   3. Gender preponderance in men by 2:1 ratio
   4. Ethnicity
      1. Most commonly affects white patients
      2. Rarely affects black or asian patients
3. Pathophysiology
   1. Idiopathic condition
   2. Usually associated with Gluten Sensitive Enteropathy
4. Symptoms: Precede lesion onset by 8 to 12 hours
   1. Intense Pruritus
   2. Skin burning
5. Signs
   1. Grouping of lesions may occur (herpetiform-like)
   2. Altered pigmentation at sites of healed lesions
   3. Polymorphous collection of lesions
      1. Urticarial wheals
      2. Vesicles
      3. Bullae
      4. Erythematous Papules
   4. Symmetric distribution of lesions on limbs and trunk
      1. Common sites
         1. Elbows and knees
         2. Buttocks and Shoulders
         3. Sacral area
      2. Uncommon sites
         1. Scalp and hairline
         2. Face and posterior neck
      3. Rare sites
         1. Palms and soles
         2. Mucus Membranes
6. Differential Diagnosis
   1. Pemphigus hermetiformis
7. Labs
   1. Complete Blood Count
      1. Eosinophilia
   2. Histology
      1. Dermal Papillae with Neutrophil microabscesses
      2. Dermal inflammatory infiltrate
      3. Subepidermal vessicles
      4. Blisters in the lamina lucida
      5. Lymphohistiocytic infiltrate at dermal vessels
   3. Immunofluorescence
      1. Granular IgA deposits in Dermal Papillae tips
   4. Other autoimmune lab associations variably present
      1. Antinuclear Antibody
      2. Antithyroid Microsomal Antibody
8. Complications
   1. Gluten Sensitive Enteropathy associated conditions
      1. Steatorrhea
      2. Abnormal D-Xylose Absorption
      3. Anemia
      4. Atrophic Gastritis
      5. Achlorhydria
      6. Gastrointestinal Lymphoma
   2. Autoimmune Conditions
      1. Thyroid Disease
      2. Type I Diabetes Mellitus
      3. Systemic Lupus Erythematosus
      4. Vitiligo
      5. Sjogren's Syndrome
9. Management
   1. Medications
      1. First-Line: Dapsone
      2. Alternative: Sulfapyradine
   2. Dietary Management
      1. Gluten-Free Diet (improvement within 6-12 months)
      2. Elemental Diet (improvement may be seen in weeks)
10. Monitoring
    1. See Dapsone (requires G6PD and monitoring of CBC)
11. Course
    1. Prolonged course over years
    2. Spontaneous remission in one third of patients
12. References
    1. Bickle (2002) Am Fam Physician 65:1861-70 [PubMed]
    2. Cotell (2000) Am J Emerg Med 18(3):288-99 [PubMed]