Skin necrosis

Introduction Skin necrosis refers to erythema, edema, blisters, and skin necrosis in the skin, and thrombosis of the dermal microvessels. Recurrent cutaneous necrotizing eosinophilic vasuclitis is a systemic red papule, hemorrhagic papule, angioedema, wheal plaque, mucositis, gingivitis, total baldness, and the like. Occasionally, skin vasculitis with ring erythema, edematous damage and blisters. The main itch. No systemic symptoms, long course of disease, a chronic recurrence process. The general prognosis is good.

Cause

(1) Causes of the disease

The cause of this disease is not clear.

(two) pathogenesis

The pathogenesis is still not very clear. Considering that eosinophils adhere to vascular endothelial cells, the presence of adhesion molecules can continuously replenish eosinophils. Eosinophils bind to cytokine-induced vascular cell adhesion molecule type 1 (VCAM-1) at endothelial cells via integrin late active antigen type 4 (VLA-4) and intercellular adhesion molecule type 1 (ICAM- 1) plays an important role in the migration of eosinophils to endothelial cells. The release of leukotrienes, C4 and platelet-activated factors by eosinophils increases vascular permeability and leads to pathological changes through the release of granule proteins, resulting in the release of histamine and mast cell histamine. The pathology is mainly dermal vascular necrotic vasculitis. Pathology showed fibrin-like necrosis in the wall, eosinophil infiltration in the entire dermis, mild or white blood cell fragmentation. The dermis is generally normal, occasionally blisters in the epidermis or infiltration of eosinophils.

Indirect immunofluorescence has a large number of major basic proteins and neurotoxins derived from eosinophils deposited inside and outside the vessel wall and the blood vessels, and can be seen in the dermis, especially in the perivascular cells (with mast cell trypsin). Dyeing) increased. Electron microscopy showed abnormalities in small blood vessel walls and endothelial cells, adhesion of eosinophils and free eosinophils, and visible endothelial cells. Eosinophils can be seen to lose cytoplasmic granules and organelles, and the chromatin of the nucleus dissolves. Abnormal endothelial cells have nuclear pyknosis, cell swelling, mitochondrial destruction, and cell membrane rupture. There are denatured large eosinophils and free particles between the collagen bundles. Immune peroxidase staining showed that VCAM-1 was deposited in small vascular endothelial cells and that VLA-4 positive large eosinophils adhered. Superficial dermal involvement of VCAM-1 is strongly positive.

an examination

Related inspection

White blood cell count platelet count (PLT) skin lesion agar diffusion test bacterial infection immunoassay

The rash is characterized by systemic red papules, hemorrhagic papules, angioedema, wheal plaques, mucositis, gingivitis, and total baldness. Occasionally ring erythema, edema damage and blisters. The main itch. No systemic symptoms, long course of disease, a chronic recurrence process.

According to clinical manifestations, laboratory tests, tissue biopsy features can be diagnosed.

The absolute count of eosinophils increased, reaching (1.4 ~ 6.2) × 10 / L, erythrocyte sedimentation rate, serum major protein (MBP) increased (<600g / L), IgE, IgA, IgG increased, serum protein electrophoresis And gamma globulin increased. Eosinophils prolonged survival in the patient's serum.

Differential diagnosis

Those who have to be identified include herpes-like dermatitis, eosinophilia syndrome, Wells syndrome, paroxysmal angioedema with eosinophilia, and polymorphic pregnancy rash. The above diseases are clinically free of hemorrhagic papules, and there are significant differences in pathology, so it is not difficult to distinguish. Churg-Strauss syndrome, clinically associated with asthma, histopathology of eosinophilic vasculitis of small to medium-sized blood vessels, or granulomatous vasculitis, and the presence or absence of white blood cell fragmentation can be identified.

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