Urticaria pigmentosa, also known as maculopapular skin mastocytosis, is the most common type of skin mastocytosis. The incidence is between 1:1000 and 1:8000, and the incidence of men and women is equal. It is a skin reaction caused by the release of various mediators from mast cells. The clinical manifestations are red or brownish red, round to oval macules, papules, and plaques, and the color gradually darkens due to the increase of pigment.
Urticaria pigmentosa (urtica pigmentosa) is a kind of mast cell disease, with round or oval pigmented spots or pigmented nodules, which become red and swollen after scratching and rubbing. It often occurs in childhood. The Nettie ship first occurred in 1969. Describe the skin manifestations of this disease, called chronic urticaria with brown spots. Unna pointed out the relationship between this disease and mast cells. Ellis first reported that in addition to the skin, other organs such as the liver, spleen, bone marrow, Mast cells can be infiltrated in lymph nodes. It is usually a benign process, and the rash can go away on its own in children.
- English name: Urticaria pigmentosa
- Treatment department: dermatology
- Multiple groups: Children, usually occur 3-9 months after birth
- Common symptoms: Red or brownish-red round, oval macules, papules, plaques, 2 to 3 cm in diameter, the color gradually darkens due to the increase in pigmentation
What causes urticaria pigmentosa?
The etiology of Urticaria pigmentosa is unknown, and there are more mast cells in the skin lesions, so the disease is considered to be a mast cell tumor. There may also be many mast cells in the liver, spleen, lymph nodes, and bone marrow of the patient, so it is classified as one of the reticuloendothelial granuloma diseases. Excessive concentration of mast cells in the skin may be related to congenital. Inoculation, tetanus injection, inadequate antiviral treatment, chickenpox or measles, and even mental stimulation can promote the appearance of this congenital abnormal disease. Skin pigmentation is due to melanin hyperplasia, while plaques and nodules are caused by a large number of mast cells. The Lewis triple reaction shows that rubbing the skin lesions can promote the release of histamine and other substances from mast cells, thereby affecting capillaries. Diastolic and permeability of the wall, so a local wind mass rash appears. Because urticaria pigmentosa disease is more common in some races, it can be seen in families with disease, and 1 parent and 1 to 2 children suffer from this disease, so it is considered to be a recessive inheritance.
Symptoms of urticaria pigmentosa
It is not difficult to diagnose typical cases, and the formation of wind masses (Parier’s sign) of pigmented skin lesions is of diagnostic value. All types of Urticaria pigmentosa have characteristic clusters of mast cells that occur between collagen fibers in the superficial dermis, and can also occur around blood vessels, hair follicles, sweat glands, and interstitial spaces. The granules of mast cells are composed of mucopolysaccharides. Giemsa and toluidine blue are metachromatic. If the granules are lost, the mast cells are not easy to identify.
In the skin lesions of the pigmented spots, there is sparse mast cell infiltration in the upper dermis, mainly distributed around the blood vessels. The mast cells have a spindle-shaped nucleus, similar to fibroblasts, with nucleated eosinophilic cytoplasm. A few eosinophils can be seen, and the melanin in the basal layer of the upper epidermis increases. In the skin lesions damaged by nodules, there are a large number of dense tumor-like mast cells infiltrating the entire dermis, and obvious granules are common. Diffuse skin lesions can be seen in banded infiltration of mast cells, and in systemic tissues, mast cell infiltration can be seen in systemic lesions. [Clinical manifestations] It is common in children, mostly in 3 to 9 months after birth, but there are also cases that occur immediately after birth. It has no effect on the growth and development of children, but children have liver and splenomegaly, ascites, and other internal organ damage.
The initial damage is often a temporary rubella mass, which often recurs and disappears in the same place later. It finally becomes persistent chloasma or pigmented nodules with uneven surfaces. A small number of patients may also have blisters on the skin lesions, and wind masses appear after scratching, which is the characteristic of this urticaria pigmentosa disease. Damages often appear in batches, varying in size, generally ranging from pea to broad bean, and the number varies, only a few are few, and more can be scattered throughout the body, some are mildly itchy, and lymph nodes are swollen. A small number of people have skin rashes that appear in adulthood, but they persist for a long time and do not disappear. Therefore, some scholars divide it into the following types:
- (1) skin type diffuse skin mast cell hyperplasia.
- (2) Systemic skin, bone, liver, spleen, and gastrointestinal damage.
- (3) Visceral spleen, bone, and gastrointestinal damage.
2. Malignant leukemia
Damage can occur at birth or in the first year after birth, and can also be seen in older children and adults. It spreads over the whole body, and the face is rare. It manifests as red or brownish-red round, oval macules, papules, plaques with a diameter of 2 to 3 cm. The color gradually darkens due to the increase in pigmentation. The rash usually presents a blistering and flushing reaction. Minor trauma-induced wind masses, that is, Darier’s sign positive is the characteristic of this urticaria pigmentosa disease. Many patients present with extensive skin scratches. Blisters occasionally appear.
Urticaria pigmentosa diagnosis
Typical cases are not difficult to diagnose of urticaria pigmentosa. Pigmented skin lesions appear red with a little friction, and the formation of wind masses (Darier sign) is of diagnostic value.
Urticaria pigmentosa treatment
Except for the adult type, patients generally heal naturally in their youth, so conservative treatment and symptomatic treatment are appropriate. The first is to avoid various irritating factors. In severe cases, medication can be considered.
1. Local treatment
If the symptoms of a single rash are severe, corticosteroids can be injected into the skin lesions and surgically removed if necessary.
2. System treatment
(1) H or a mast cell membrane stabilizing agents 1 receptor antagonist can effectively control the symptoms, to itching, reducing the onset of effect, such as ① newly reported tranilast orally, with good results. ② Disodium cromoglycate has the effect of stabilizing the mast cell membrane and has a good curative effect. It is most recommended. ③The antihistamines ketotifen, chlorpheniramine, cyproheptadine, and hydroxyzine are also commonly used drugs.
(2) Combined application of mast cell membrane stabilizers or H 1 receptor antagonists (such as ketotifen, chlorpheniramine, cyproheptadine, hydroxyzine) and H 2 receptor antagonists (such as cimetidine or ranitidine) D) Joint application.