Clinical Features of Dermatitis Herpetiformis
Dermatitis herpetiformis presents as intensely itchy, blistering skin lesions with characteristic distribution on the elbows, knees, buttocks, and scalp, representing the cutaneous manifestation of celiac disease. 1, 2
Primary Skin Manifestations
- Lesion morphology: Urticarial papules, small vesicles, and blisters that are intensely pruritic 1, 3
- Distribution pattern: Predilection sites include elbows, knees, buttocks, and scalp, though other sites may be involved 2, 4
- Symmetry: Lesions typically appear in a symmetrical distribution 5
- Persistence: The eruption tends to be chronic and persistent, with only 10-15% of patients experiencing spontaneous remission over 25 years 3
Characteristic Symptoms
- Intense pruritus: The hallmark symptom is severe itching that often precedes visible skin lesions 2, 4
- Burning sensation: Patients frequently describe a burning quality to the discomfort 1
- Urticarial plaques: Raised, hive-like lesions that may precede blister formation 3
Diagnostic Skin Findings
- Granular IgA deposits: Pathognomonic finding of granular immunoglobulin A deposits in the papillary dermis on direct immunofluorescence of perilesional skin 2, 6
- Biopsy location: The immunofluorescence must be performed on uninvolved perilesional skin, not on the blister itself 3
- Diagnostic requirement: The diagnosis should not be made in the absence of these characteristic IgA deposits 3
Associated Gastrointestinal Features
- Enteropathy: Two-thirds of patients have small intestinal villous atrophy identical to celiac disease 3
- Subclinical gut involvement: The remaining third show celiac-type inflammatory changes with increased lymphocytic infiltration of the epithelium, even with normal villous architecture 6, 3
- Minimal GI symptoms: Overt gastrointestinal symptoms are rare in DH compared to classic celiac disease 5
Demographic and Temporal Characteristics
- Age of onset: Mean age at diagnosis is currently 40-50 years, which has increased significantly in recent decades 5
- Gender distribution: Slightly more common in males, in contrast to celiac disease which shows female predominance 2, 6
- Genetic predisposition: First-degree relatives have a 5% risk of developing either DH or celiac disease 6
Serological Markers
- TG2 antibodies: Tissue transglutaminase (TG2) antibodies are present in serum and support the diagnosis 2
- TG3 antibodies: IgA antibodies against epidermal transglutaminase (TG3) are found in the skin 6
- Important caveat: Absence of circulating antibodies does not exclude DH diagnosis 2
Associated Autoimmune Conditions
- Thyroid disease: Increased incidence requiring annual screening 3
- Pernicious anemia: Higher prevalence than general population 3
- Insulin-dependent diabetes: Elevated risk necessitating regular screening 3
Common Pitfall to Avoid
The most critical diagnostic error is attempting to biopsy the blister itself rather than perilesional uninvolved skin for immunofluorescence, which will not show the pathognomonic granular IgA pattern needed for diagnosis 3.