Overview
Definition:
Dermatitis herpetiformis (DH) is a chronic, intensely pruritic, papulovesicular skin eruption that is strongly associated with celiac disease
it is considered the cutaneous manifestation of celiac disease in most individuals.
Epidemiology:
DH affects approximately 1 in 10,000 individuals
It typically presents in young adults and adolescents, with a slight female predominance
In pediatrics, it is less common but can occur, often presenting later in childhood or adolescence
A significant majority (up to 90%) of individuals with DH have histologically confirmed celiac disease, even in the absence of overt gastrointestinal symptoms.
Clinical Significance:
Recognizing DH in children is crucial as it signals underlying celiac disease, a condition that can lead to significant nutritional deficiencies, impaired growth, and long-term complications if left untreated
Early diagnosis and management are vital for improving patient quality of life and preventing sequelae.
Clinical Presentation
Symptoms:
Intense itching (pruritus) that is often burning and excoriating
Symmetrical distribution of lesions, typically on elbows, knees, buttocks, and sacrum
Small vesicles, papules, and excoriations, often appearing as urticarial plaques
Absence of gastrointestinal symptoms in a significant proportion of pediatric patients.
Signs:
Characteristic lesions include grouped papules and vesicles
Excoriations are prominent due to intense itching
Lesions are often symmetrically distributed on extensor surfaces (elbows, knees, buttocks, sacrum)
Mucous membranes are usually spared
Vital signs are typically normal unless secondary infection from scratching occurs.
Diagnostic Criteria:
Clinical suspicion based on the characteristic rash distribution and intense pruritus
Skin biopsy showing characteristic granular IgA deposits in the dermal papillae on direct immunofluorescence microscopy is the gold standard
Detection of IgA anti-tissue transglutaminase (anti-tTG) antibodies and IgA anti-endomysial (anti-EMA) antibodies in serum confirms the diagnosis of celiac disease
Histopathology of a small intestinal biopsy may reveal villous atrophy, crypt hyperplasia, and increased intraepithelial lymphocytes, confirming celiac disease.
Diagnostic Approach
History Taking:
Detailed history of the onset, duration, and evolution of the skin rash
Severity and pattern of pruritus
Any associated gastrointestinal symptoms (diarrhea, constipation, abdominal pain, bloating, poor weight gain)
Family history of celiac disease or autoimmune disorders
Dietary history, including gluten intake
Medication history.
Physical Examination:
Thorough skin examination to assess the morphology, distribution, and symmetry of lesions
Note excoriations, papules, vesicles, and urticarial plaques
Examine extensor surfaces of elbows and knees, buttocks, and sacrum
Check for signs of malnutrition or growth delay
Evaluate for other signs of autoimmune disease.
Investigations:
Skin biopsy for direct immunofluorescence (DIF) microscopy: demonstrates granular IgA deposits in the dermal papillae
Serological tests for celiac disease: IgA anti-tissue transglutaminase (anti-tTG) antibodies and IgA anti-endomysial (anti-EMA) antibodies
note that IgA deficiency can lead to false-negative results, so total IgA levels should also be checked
Total IgA levels: to rule out selective IgA deficiency
Small intestinal biopsy: recommended to confirm celiac disease, especially if serological tests are equivocal or if there are gastrointestinal symptoms
typical findings include villous atrophy, crypt hyperplasia, and increased intraepithelial lymphocytes.
Differential Diagnosis:
Other forms of pruritic dermatoses: eczema, scabies, urticaria, allergic contact dermatitis
Other blistering disorders: bullous pemphigoid (more common in older adults), epidermolysis bullosa
Pityriasis rosea
Insect bites.
Management
Initial Management:
Strict adherence to a lifelong gluten-free diet (GFD) is the cornerstone of treatment for both DH and celiac disease
Symptomatic relief of pruritus.
Medical Management:
Gluten-free diet: This is the primary treatment
Symptoms of DH typically improve within weeks to months of strict adherence
Medications for pruritus: Dapsone (diaminodiphenyl sulfone) is highly effective for symptomatic relief while the GFD takes effect
Pediatric Dapsone dosage: typically 0.5-1 mg/kg/day divided into 1-2 doses
Monitor for side effects of dapsone, including hemolytic anemia, methemoglobinemia, and peripheral neuropathy
Sulfasalazine may be an alternative if dapsone is contraindicated or not tolerated
Topical corticosteroids: can be used for localized, severe itching, but systemic treatment is usually required.
Surgical Management:
Not applicable for DH or celiac disease.
Supportive Care:
Nutritional assessment and supplementation if deficiencies are identified due to malabsorption
Education on the importance of a lifelong gluten-free diet
Support groups for patients and families
Regular follow-up to monitor adherence to the GFD and assess for complications.
Complications
Early Complications:
Intractable pruritus and excoriations leading to secondary bacterial infections
Anemia (iron deficiency, folate deficiency, B12 deficiency) due to malabsorption
Neutropenia or hemolytic anemia due to dapsone therapy.
Late Complications:
Osteoporosis or osteopenia due to calcium and vitamin D malabsorption
Increased risk of other autoimmune diseases (e.g., type 1 diabetes, autoimmune thyroiditis)
Increased risk of certain malignancies, particularly intestinal lymphomas (e.g., T-cell lymphoma), though the risk is significantly reduced with strict GFD adherence
Growth failure in children if celiac disease is diagnosed late.
Prevention Strategies:
Strict, lifelong adherence to a gluten-free diet is paramount
Regular monitoring for nutritional deficiencies and bone health
Patient and family education on celiac disease and DH management
Early diagnosis and treatment of celiac disease in at-risk individuals.
Prognosis
Factors Affecting Prognosis:
Adherence to the gluten-free diet is the most significant factor
Early diagnosis and prompt initiation of treatment
Presence and severity of associated autoimmune conditions
Degree of intestinal villous atrophy at diagnosis.
Outcomes:
With strict adherence to a gluten-free diet, the skin lesions of DH typically resolve completely within 1-2 years
Gastrointestinal symptoms improve, and nutritional status normalizes
Long-term prognosis is generally good, with a significant reduction in the risk of complications
Recurrence of DH can occur with accidental gluten ingestion.
Follow Up:
Regular follow-up appointments with a pediatrician, gastroenterologist, and dermatologist are recommended
Monitor for adherence to the GFD
Annual serological screening for celiac disease antibodies is advised
Periodic assessment of nutritional status, bone mineral density, and growth parameters
Education on recognizing symptoms of gluten exposure and managing accidental ingestions.
Key Points
Exam Focus:
DH is the cutaneous manifestation of celiac disease
treat with a strict gluten-free diet
Dapsone provides rapid symptomatic relief but is not a substitute for the GFD
Direct immunofluorescence showing granular IgA deposits is diagnostic for DH
Celiac serology (anti-tTG, anti-EMA) is crucial
Consider IgA deficiency.
Clinical Pearls:
The itch in DH is often described as unbearable
Look for lesions on elbows, knees, buttocks, and sacrum
Always consider celiac disease in a child with this rash pattern, even without GI symptoms
Skin biopsy for DIF is the gold standard for DH diagnosis, while intestinal biopsy confirms celiac disease histology
Educate families thoroughly on the strictness of the GFD.
Common Mistakes:
Treating DH with dapsone indefinitely without emphasizing the gluten-free diet
Failing to perform direct immunofluorescence on a skin biopsy
Not screening for celiac disease serologically in patients with DH
Prescribing dapsone without monitoring for hematologic side effects
Attributing the rash solely to scratching without considering an underlying condition.