Linear IgA bullous dermatosis
Introduction
Introduction to linear IgA bullous skin disease Linear IgA bullous dermatoses (LABD) or linear IgA dermatosis (linearIgAdematosis) is only 30% positive for HLA-B8 because of its basement membrane linear IgA deposition without gluten-sensitive enteropathy. It is an independent disease completely different from bullous pemphigus and herpetic dermatitis. Another chronic chloasthesis of childhood is a rare disease that occurs mainly in children under 5 years old and has the same type. The basement membrane has a homogeneous IgA linear deposition, so some people think that the two are different manifestations of the same disease. Here, we classify the two diseases as a disease. Linear IgA bullous skin disease mainly occurs in Young people are mostly around 40 years old, women are slightly more than men, and children with linear bullous skin disease are seen in children under 5 years of age. basic knowledge The proportion of illness: 0.006%-0.008% Susceptible people: no specific population Mode of infection: non-infectious Complications: impetigo
Cause
The cause of linear IgA bullous skin disease
(1) Causes of the disease
The cause is still unclear and is currently thought to be related to autoimmune factors.
(two) pathogenesis
Due to the dermal-bound basement membrane linear IgA deposition, and IgA is a secretory immunoglobulin, its source has not yet been determined. Indirect immunofluorescence revealed that the circulating anti-basal membrane IgA antibody is located on the epidermal side of saline-separated skin. A few studies reported that the antigen is located on the dermis side, indicating that there may be more than one target antigen in this disease. Immunoelectron microscopy found that there are three ways to deposit antibodies to linear IgA skin disease, one is deposited on transparent plates and the other is deposited. Above the dense plate and below, the third is above and below the dense plate, while the IgA deposits in children with chronic bullous skin disease are also located in the transparent plate, the dense plate and below, and these findings further support the participation of multiple antigens as adults. And children's linear IgA deposition of target antigens, preliminary studies found that the antigen molecular weight of 97kDa, 285kDa and 120kDa three proteins, the above studies show that linear IgA bullous skin disease and children with chronic bullous skin disease have many common antigens, detailed The mechanism needs further study.
Taking certain drugs such as vancomycin, lithium preparations can cause the disease to occur, the condition is relieved after stopping the drug, and the recurrence of the drug is re-applied. The mechanism of the drug causing minor illness is still unclear, but it is clear that certain drugs may cause IgA deposits on the skin leading to disease.
Prevention
Linear IgA bullous skin disease prevention
Long-term maintenance therapy is the key to preventing recurrence.
It has now been established that acquired bullous skin disease is a group of autoimmune skin diseases. Once the lesion is controlled by glucocorticoids or other immunosuppressive agents, it is necessary to gradually reduce the dose and take it for a long time. Pemphigus usually takes 3 to 5 years, and bullous pemphigoid takes 2 to 3 years. Sudden withdrawal and rapid drug reduction are important causes of recurrence.
Complication
Linear IgA bullous skin disease complications Complications, impetigo
Pemphigus antibody-induced acantholytic is a special immunological injury that does not require complement or lymphocyte involvement and is a special tissue damage induced by autoantibodies. The process of acantholytic release can be summarized as: a pemphigus antibody is produced by the action of an initial factor that binds to the corresponding antigen on the epidermal cell membrane, causing the epidermal cells to release or activate the protease, which decomposes between the intercellular cells. The matrix destroys the adhesion between normal cells and cells, which leads to the release of the acanthosis.
Symptom
Linear IgA bullous skin disease symptoms Common symptoms Itching papules Herpes secondary infection Oral ulcer Mucosal damage bullae (with purulent liquid)
1. Adult type:
More common in young and middle-aged, the damage is pleomorphic, can be ring or group of papules, blisters and bullae, symmetrically distributed on the extremities of the limbs, such as elbow, knee and hip, consciously itching, clinical manifestations and herpes-like dermatitis difficult to identify But the degree of itching is lighter than herpes-like dermatitis.
2. Children's type:
Common in children under 5 years old, the incidence of girls is slightly higher than that of boys. The most common characteristic damage is tension blisters on the inflammatory basal. These lesions are most common in the vulva and perioral areas, often in clusters, new lesions. Often appearing around the old skin lesions, the blister forms a "neck collar"-like change, the patient often feels itching or itching, the onset is sudden, a lot of tension blisters are formed, the blister rupture can be secondary infection, mucosal damage is less common, degree The severity is different, and the damage to the mouth and conjunctiva is slightly common. The mild manifestations are asymptomatic oral ulcers and erosions, severe contusion-like conjunctiva and oral damage.
Examine
Examination of linear IgA bullous skin disease
Histopathology: skin lesions are subepidermal blisters, a large number of neutrophils accumulate along the basement membrane, often in the top of the dermal papilla, lymphocytic infiltration can be around the superficial dermal blood vessels, the author believes that histopathology and herpes The difference between dermatitis is that there are fewer microscopic abscesses of the dermal papilla and a more diffuse basement membrane with neutrophil infiltration. Most authors believe that histopathological linear IgA bullous skin disease and herpes-like dermatitis are It is difficult to identify, electron microscopy shows that the blister is formed in the transparent plate or the area under the dense plate. Direct immunofluorescence shows that the skin around the blister has a homogeneous linear IgA deposition on the basement membrane. Some patients have IgM, IgG deposition, and indirect immunofluorescence. Low titer IgA antibodies against the basement membrane were detected in the patient's serum, and the positive rate in adults was lower than in children.
Diagnosis
Diagnosis and diagnosis of linear IgA bullous skin disease
diagnosis
According to the clinical manifestations, histopathological changes are similar to herpes-like dermatitis and bullous pemphigoid. Direct immunofluorescence examination reveals that the basement membrane of the skin around the lesion has IgA linear deposition, which can basically establish the diagnosis, adult and child type. Slightly different, adult skin lesions are similar to herpes-like dermatitis, children are mostly pre-school morbidity, bullae occurs in the face, around the mouth, around the vulva, the course of disease is self-limiting, and later the disease gradually reduced, mostly before puberty .
Differential diagnosis
1. The disease should be differentiated from bullous herpes and herpes-like dermatitis.
2. Bullous epidermolysis: Many cases occur soon after birth, often have a positive family history, bullae are often located in stress and friction parts, of which dysplastic can be blood blister, leaving atrophic scar after healing And pigment abnormalities, accompanied by nails, mucous membranes or tooth dysplasia and hair loss.
3. Acquired bullous epidermolysis: adult onset, susceptible to blisters, scars, millet rash, direct immunofluorescence examination of the basement membrane with IgG linear deposition can be identified.
