What islinearIgAbullousdisease?
Linear IgA bullous disease is a rare,autoimmune, blistering disease in which blisters form in the skin andmucousmembranes including the mouth,genitalmucosae, andconjunctivae.
Its name comes from the characteristic findings of lineardepositionofimmunoglobulinA (IgA) at the dermo-epidermaljunction (at thebasement membranezone), which is demonstrated byimmunofluorescence. It is also called linear IgA bullousdermatosisand in children, it may be known as linear IgA dermatosis of childhood orchronicbullous disease of childhood.
Who gets linear IgA bullous disease?
Linear IgA bullous dermatosis is rare; the annualincidencein some countries is reported to be approximately 0.5–2 cases per million people. It can occur in both adults and children.
In adults, disease onset is more common in the sixth decade. In children, disease onset is more common during preschool age (~4.5 years old).
It has been suggested that it may be more common in children indevelopingcountries.
Linear IgA bullous disease can be associated with some underlying diseases such asinflammatorybowel disease (Crohn, ulcerativecolitis),solidandlymphoidmalignancies, and rheumatoidarthritis. Unlikedermatitisherpetiformis, where the deposits of IgA on direct immunofluorescence aregranular, there is no association withgluten sensitive enteropathy.
What causes linear IgA bullous disease?
Linear IgA bullous dermatitis can beidiopathic或药物引起。尽管它是be an autoimmune disease, the exact mechanism oflesiondevelopmentis not well understood.
Geneticinvolvement may contribute to the development of chronic bullous disease of childhood where a number of humanleukocyteantigentypes have been linked.
Drug-induced IgA disease usually resolves on withdrawal of the offending drug. Drugs that may be implicated include:
- Vancomycin (most frequently associated drug)
- Non-steroidalanti-inflammatorieseg, diclofenac, naproxen
- Captopril
- Trimethoprim + sulphamethoxazole
- Amiodarone
- Furosemide
- Ciclosporin
- Glibenclamide
- Lithium
- Penicillins
- Cephalosporins (cefalosporins)
- Phenytoin
- Sodium hypochlorite (bleach)
Linear IgA bullous disease may present astoxicepidermal necrolysis (TEN)— a severecutaneousadverse drug reactionwithwidespreadblistering and painful loss of skin. A few cases have been described in which direct immunofluorescence has revealed characteristic linear deposits of IgA.
Drug-induced TEN-like worsening of linear IgA disease
What are the clinical features of linear IgA bullous disease?
Blisters
- Location:
- May occur anywhere on the body
- In children, usually found on the lower abdomen, thighs, and groin
- In adults, the limbs, face, and trunk are more commonly affected
- Approximately 50% of people have blisters andulcerson the lips and inside the mouth.
- Presentation:
- Round or oval filled with clear fluid
- Small (vesicles) or large (bullae)
- May arise from normal, red flat, or elevated patches of skin
- Typically found in rings (annularlesions) in children — new blisters tend to arise in a ring around an existing blister known as the ‘string of beads’sign
- Groups of small blisters may be described as a ‘cluster of jewels’ or ‘crown of jewels’.
Secondary lesions
- Crusts, scratch marks, and sores.
- Lesions seen asinflammation,erosions, ulcers, and scarring may occur alongmucous membranes.
Pruritus
- Common
- Intensity of itching varies between individuals
Linear IgA bullous disease
What are the complications of linear IgA bullous disease?
Eye involvement may result in irritation, dryness,photosensitivity, blurred vision, corneal scarring, and even blindness.
How is linear IgA bullous disease diagnosed?
历史和g检查通常是不够的ive a definitive diagnosis as clinical signs and symptoms often resemble other blistering conditions.
Linear IgA bullous disease is best diagnosed by performingdirect immunofluorescenceof skinadjacentto a blister; it reveals a linear band of IgA at the dermo-epidermal junction.
A thorough medication history should also be taken to determine possible drugaetiology.
Other tests that may be used include:
- Indirect immunofluorescence— IgAantibodiescan also be detected by this blood test and may be helpful especially when abiopsyis not possible.
- Lightmicroscopy— however, findings may not be definitive as they may resemble other diseases such asdermatitis herpetiformis.
Direct immunofluorescence in linear IgA bullous dermatosis
What is thedifferential diagnosisfor linear IgA bullous disease?
- Bullous impetigo
- Bullous pemphigoid
- Dermatitis herpetiformis—differentiatedby its granular IgA deposition (not linear)
- Epidermolysis bullosa acquisita
- Pemphigoid gestationis
What is the treatment for linear IgA bullous disease?
Linear IgA bullous disease usually improves or clears when treated withdapsone, animmunomodulatorysulphone. Its success as treatment is well-established and improvement can usually be seen within just 2 to 3 days of drug initiation.
Other medications that have been used to treat linear IgA disease include:
- Topicalcorticosteroids(in some cases,systemiccorticosteroids)
- Tetracycline antibiotics
- Erythromycin
- Sulfonamides
- Colchicine
- Mycophenolate mofetil
- Rituximab.
What is the outcome for linear IgA bullous disease?
Linear IgA bullous disease generally has a goodprognosis. Approximately 30–60% of adult patients experience spontaneousremissionbut usually only after years of disease. In children, spontaneous disease remission usually occurs after 2–4 years of disease onset.
However in some patients, long-term treatment may be required if reduction in dose of active treatment results in further blistering.
Drug-induced linear IgA disease has good outcomes where remission occurs in most cases within 2–6 weeks of discontinuation of the offending drug.