Bullous pemphigoid

Introduction to bullous pemphigus Bullous pemphigoid (hullouspemphigoid) is a bullous disease that is more common in the elderly. The blister wall is thicker and less prone to rupture. Histopathology is the epidermis bullae, and immunofluorescence shows the basement membrane with immunoglobulin self-deposition. The course of the disease is chronic and the prognosis is good. basic knowledge The proportion of illness: 0.0035% Susceptible people: no special people Mode of infection: non-infectious Complications: pruritus

Causes of bullous pemphigoid

(1) Causes of the disease

The cause is not fully understood. It is generally considered to be an autoimmune disease. Direct immunofluorescence reveals a linear C3 and IgG deposit on the basement membrane of the skin around the lesion. Indirect immunofluorescence found that 70% to 85% of the pemphigoid patient serum has Anti-epidermal basement membrane IgG circulating antibodies, a considerable number of patients also have anti-basement membrane IgE antibodies, damage to the presence of a large number of eosinophils and degranulation, so it is possible that type I allergic reactions involved in skin lesions, will be immune The fluorescent reaction substrate was first incubated in 1 M NaCl, separating the epidermis and dermis from the transparent plate, the sensitivity of indirect immunofluorescence was increased, and the pemphigus-like antibody was bound to the top of the saline-dissociated artificial blisters, ie the substrate. The bottom of the cell.

(two) pathogenesis

There was no correlation between the antibody titer of bullous pemphigus and the severity of the disease. In addition to complement C3, other components of the classical and alternative complement activation pathways and the complement regulatory protein 1 H were also deposited in patients with bullous pemphigoid. In the basement membrane zone, activated complement components are also seen in the bullous fluid. In vitro experiments have also demonstrated that pemphigoid antibodies can be combined with classical and alternative pathways of complement components deposited in the dermal basement membrane band. These studies have demonstrated that bullous IgG can be classical. The pathway activates complement and activates the complement replacement pathway with a C3 amplification mechanism.

Immunoelectron microscopy confirmed that the pemphigus antigen plays an important role in the connection between basal cells and the basement membrane. The antibody binds to the cytoplasmic plate inside and outside the basal cells, and immunofluorescence, etc., pemphigoid antigen There are two different molecules, one is 230kDa, a clone of the cDNA encoding this molecule of BPAG1, which shows a gene family containing fibroblastin 1 and the ultrastructure BPAG1 is located in the semi-bridged plaque.

Animal experiments have shown that inhibition of BPAG1 function, bullous pemphigoid antibody has no pathogenic effect, and when anti-BPAG1 antibody binds to BPAG1 antigen, it can activate complement and cause inflammation and subdermal vesicle formation, as measured by immunochemical methods. Another antigen is a 180kDa (also known as 166 and 170kDa) molecule, now called BPAG2 or XVII collagen fiber, which is a transmembrane molecule. The chromosomal location of cDNA clones confirms that BPAG1 and BPAG2 are completely differently encoded by different genes. The molecular compound, BPAG1 is located only in the cell, and BPAG2 is located in the cell membrane, which is partially located in the cell, partially in the cell, and is a typical transmembrane molecule. The pemphigus antibody against these two antigens is in vitro. And in vivo experiments have proved to be etiological. It is currently believed that the mechanism of pemphigoid damage formation may be that the antibody binds to the bullous pemphigoid antigen, thereby activating the classical complement pathway and simultaneously activating the C3 amplification mechanism. Complement components cause leukocyte chemotaxis and mast cell degranulation, mast cell products cause chemotaxis of eosinophils, and finally white Cells and mast cells release proteases results in true skin separation, it has also been proposed pemphigoid antibody binding results hemidesmosome BPAG2 dysfunction, leading to loss of basal cells are connected to the basement membrane separating the epidermis true bullae formation.

Certain drugs can also cause pemphigoids, such as sulfasalazine sulphate, penicillin, furosemide, diazepam, etc. 5-Fu topical application and X-ray irradiation can also cause limited pemphigoid, bullous There are also many reports of pemphigus associated with other diseases, such as polymyositis, pemphigus vulgaris, herpes-like dermatitis, SLE, ulcerative colitis, nephritis, polyarthritis, lichen planus and psoriasis. Etc. No reports of minor illnesses related to infection.

Bullous pemphigoid prevention

Eliminate the effects of cross-reactive foreign antigens or eliminate the effects of various factors affecting the changes of autoantigens, such as preventing and treating infections, and avoiding the use of certain drugs that are prone to induce autoimmune reactions.

Bullous pemphigoid complications Complications pruritus

The course of the disease is chronic, the prognosis is good, and there is generally no special complication.

Bullous pemphigoid symptoms Common symptoms Fever, papules, herpes, mucous membrane damage, crusted scales

Symptoms of damage occur in the neck, armpits, groin, inner thighs and upper abdomen. Symptoms of blistering often occur on normal or erythematous skin (Figures 1-3). Blisters can develop blood blisters and erosions as the disease progresses. Scarring, when vesicles occur in groups, similar to herpes-like dermatitis, the size from cherry to walnut is large, the maximum is 7cm. If there is no secondary infection after rupture, it often scabs quickly, and the erosion surface heals faster. Pigmentation, occasionally atrophic scars, sometimes combined with millet rash, Nissl's sign negative, mucosal damage occurred in about 20% to 30% of patients, clear painful erosion, mainly oral mucosa, pharynx, larynx and genitals Mucosal damage at the site is rare.

Early damage to itching is obvious, there is pain after erosion, sometimes itching is the only symptom in the months before the blisters occur, but also loss of appetite, weight loss, weakness, fever and other symptoms.

1. Diagnostic points

(1) Occurs in the elderly, there are tension bullae on erythema or normal skin, the blister wall is not easy to rupture, and the Nissl sign is negative.

(2) Mucosal damage is small and slight.

(3) The pathological changes are subepidermal blister, the basement membrane carries IgG in a linear form, and the serum has an anti-basement membrane with autoantibodies.

2. Several special types of pemphigoid The clinical manifestations of some bullous pemphigoids may be very atypical, and should be diagnosed according to histopathology and immunopathology.

(1) erythematous and edematous bullous pemphigoid: This type is relatively common, clinically similar to polymorphic erythema and chronic urticaria, vesicles are less, often no blister occurs in the early stage, histopathology is epidermis Under the blisters, direct immunofluorescence is the basal membrane with IgG and C3 linear deposition, sometimes repeated biopsy, the positive rate of indirect immunofluorescence is only about 30%.

(2) vesicular bullous pemophigoid: This type is very rare, blister often occurs in the trunk, can also be seen in the limbs, can have severe itching and burning, very similar to herpes-like dermatitis.

(3) Seborrheic pemphigoid: This disease is more common in elderly women, clinically similar to erythematous pemphigus, histology and immunopathology in line with pemphigoid, pemphigoid antibody drops Eosinophilia is not uncommon with a low degree of 1:40 to 1:80. It has been reported that methylprednisolone has a better effect and can rapidly reduce the amount of hormone.

(4) localized bullous pemphigoid (localized bullous pemphigoid): this disease is also more common in the elderly, lesions are often limited to a certain part of the body, such as the scalp or lower limbs, often symmetrically present, the predilection is in Calf, large blisters occur on normal skin, often without any symptoms, histopathological examination for epidermis blister, characterized by bullous pemphigoid, this disease should be differentiated from scar pemphigoid.

(5) Proliferative bullous pemphigoid: also known as pemphigoid vegetans. This disease may be sensitive to bacterial infections such as pemphigoids in the intervening site.

Clinically very rare, the appearance is similar to bullous pemphigoid and proliferative pemphigus, the damage is suppurative verrucous hyperplasia, mainly in the folds, suede and scale spots found in the scalp, face and so on.

Histopathologically, there is a typical bullous pemphigoid with papillary-like hyperplastic changes. The disease should be differentiated from proliferative pemphigus, pigmented blastomycosis, pyoderma, bronchitis, and iodine.

(6) Sweat-like pemphigus (dyshidrosiform pemphigoid): This is a rare variant of bullous pemphigoid, manifested in the palmar area, with persistent vesicular damage similar to sweat herpes, vesicular bullous The damage may be hemorrhagic. Bullous and erythematous lesions may occur in other parts of the body during the development of the disease. Histopathology and immunopathological examination are completely consistent with bullous pemphigoid. Treatment with DDS and low dose of prednisone Pine, has a good effect.

(7) Nodular bullous pemphigoid: also known as hyperkeratoic bullous pemphigoid is a very rare variant of bullous pemphigoid It consists of keratinized nodules that contain disseminated subepidermal vesicles on the lower extremities and upper extremities. The disease process is extremely slow, and corticosteroids and immunosuppressive agents are not ideal.

Bullous pemphigoid examination

Indirect immunofluorescence of peripheral blood from patients with active skin lesions indicates that there is anti-BPAG1 or BPAG2 IgG antibody in the blood circulation. The substrate of indirect immunofluorescence assay is suitable for the guinea pig or monkey esophagus. The skin acts as a substrate, and IgG and C3 are deposited on the basement membrane of the skin around the bullae and bullae. The direct immunofluorescence of the lesions indicates that the basement membrane has banded fluorescence (Fig. 3), and immunoelectron microscopy shows immunoglobulin deposition. In the transparent plate of the basement membrane of the skin, it coincides with the site where the bullous occurs.

Almost half of the patients have elevated serum IgE, and consistent with the titer of IgG anti-basement membrane antibody, IgE antibody level is related to the degree of pruritus, blood eosinophils can be significantly increased, erythrocyte sedimentation rate can be increased, serum white The protein is falling.

Histopathology: microbubbles are present at the true epidermal junction of the skin at the edge of the bullae. The bullella is a micro-tumor with eosinophils around the dermal papilla around the epidermis. The top is a full-thickness epithelium. There is no degeneration of the epidermis. The bullae contain serum, fibrin and a large number of eosinophils. Eosinophils can also be seen in the epidermis. Depending on the degree of the disease, inflammation of the blood vessels can be seen in the dermis, swelling of the endothelium, thickening of the blood vessel wall, and around the blood vessels. Lymphocytes and neutrophils infiltrated, in the skin of the bullae and erythema, direct immunofluorescence showed linear uniform IgG and complement C3 deposition, 70% ~ 80% of patients with indirect immunofluorescence test serum The subepithelial basement membrane was circulated with antibodies, and the blister was found under the transparent plate by electron microscopy.

Diagnosis and identification of bullous pemphigoid

1. The disease needs to be differentiated from herpes-like dermatitis and pemphigus vulgaris.

(A) bullous polymorphic erythema is more common in young people, rash morphological, mucosal damage is extensive and serious, acute onset, often accompanied by fever and other systemic symptoms, skin damage immunofluorescence examination of the basement membrane band without fluorescence.

(B) Acquired bullous epidermis relaxation This disease is more common in the elderly, vesicles occur in the extremities, such as the hands and feet, elbow and knee extension and other vulnerable parts, pathological changes are also epidermis, but within the dermis For neutrophil infiltration without eosinophil infiltration, the skin was lysed with 1 mol/L NaCl for indirect immunofluorescence, the fluorescence of the disease was isolated on the dermal side of the skin, and the fluorescence of bullous pemphigoid was isolated from the skin. The epidermis side.

2. Bullous polymorphic erythema is acute, rare in the elderly, and mucosal damage is severe and common.

3. Linear IgA bullous skin disease in adults, the age of onset is less than that of pemphigus, blister is often arranged in an arc, asymmetric distribution, immunofluorescence with basement membrane with linear IgA deposition.

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