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Pemphigus is a group of rare autoimmune diseases that cause blistering of the skin and mucous membranes (mouth, nose, throat, eyes, and genitals). Some forms of the disease, including the most common form, may be fatal if left untreated.
There are several types of pemphigus and other similar blistering disorders. The type of disease depends on what level in the skin the blisters form and where they are located on the body. Blisters always occur on or near the surface of the skin, which is called the epidermis. People with pemphigus vulgaris, for example, have blisters that occur within the lower layer of the epidermis, while people with pemphigus foliaceus have blisters that form in the topmost layer. The type of antibody that is attacking the skin cells may also define the type of disease present.
Pemphigus vulgaris is the most common type of pemphigus in the United States. Soft and limp blisters appear on healthy-looking skin and mucous membranes. The sores almost always start in the mouth. The blisters of pemphigus vulgaris form within the deep layer of the epidermis, and are often painful. Blistered skin becomes so fragile that it may peel off by rubbing a finger on it. The blisters normally heal without scarring, but pigmented spots may remain for a number of months.
Pemphigus vegetans is a form of pemphigus with thick sores in the groin and under the arms.
Pemphigus foliaceus involves crusted sores or fragile blisters that often appear first on the face and scalp and later on the chest and other parts of the body. Unlike pemphigus vulgaris, blisters do not form in the mouth. The sores are superficial and often itchy, and are rarely as painful as pemphigus vulgaris blisters. There may also be loose, moist scales on the skin.
IgA pemphigus is a blistering disorder in which a different type of antibody binds to the cell surface of epidermal cells. This disease is different from other forms of pemphigus because it involves a different type of antibody (called IgA) than other types. The disease may result in blisters similar to those seen in pemphigus foliaceus, or it may involve many small bumps containing pus. This is the most benign, or least harmful, form of pemphigus.
Paraneoplastic pemphigus is a rare disease that is distinct from pemphigus, but shares some features of it. It occurs in people with certain types of cancer, including some lymphomas and leukemias. It often involves severe ulcers of the mouth and lips, cuts and scarring of the lining of the eye and eyelids, and skin blisters. Because the antibodies also bind the airways, patients may develop life-threatening problems in the lungs. This disease is different from pemphigus, and the antibodies in the blood are different. Special tests may be needed to identify paraneoplastic pemphigus.
Pemphigoid is also a blistering disorder caused by autoimmune problems that result in an attack on the skin cells by a person's own antibodies. Pemphigoid produces a split in the cells where the epidermis and dermis, the layer below the epidermis, meet, causing deep, tense blisters that do not break easily. Pemphigus, on the other hand, causes a separation within the epidermis, and the blisters are soft, limp, and easily broken. Pemphigoid is seen most often in the elderly and may be fatal. Usually, both pemphigus and pemphigoid are treated with similar medications. Severe cases may require different treatment.
A diagnosis of pemphigus has several parts:
A visual examination by a dermatologist. The doctor will take a complete history and physical exam, noting the appearance and location of the blisters.
A blister biopsy. A sample of a blister is removed and examined under the microscope. The doctor will look for cell separation that is characteristic of pemphigus, and will also determine the layer of skin in which the cells are separated.
Direct immunofluorescence. A biopsy of a skin sample is treated in the laboratory with a chemical compound to find the abnormal desmoglein antibodies that attack the skin. The specific type of antibodies that form may indicate what type of pemphigus exists.
Indirect immunofluorescence. Sometimes called an antibody titre test, a sample of blood is tested to measure pemphigus antibody levels in the blood and help determine the severity of the disease. Once treatment begins, this blood test may also be used to find out if treatment is working.
Pemphigus is a serious disease, and it is important to do all of these tests to confirm a diagnosis. No single test is right all of the time.
Because it is rare, pemphigus is often the last disease considered during diagnosis. Early diagnosis may permit successful treatment with only low levels of medication, so consult a doctor if you have persistent blisters on the skin or in the mouth. In the most common form of pemphigus (pemphigus vulgaris), the mouth is often the first place that blisters or sores appear.
Normally, our immune system produces antibodies that attack viruses and harmful bacteria to keep us healthy. In people with pemphigus, however, the immune system mistakenly attacks the cells in the epidermis, or top layer of the skin, and the mucous membranes. The immune system produces antibodies against proteins in the skin known as desmogleins. These proteins form the glue that keeps skin cells attached to keep the skin intact. When desmogleins are attacked, skin cells separate from each other and fluid can collect between the layers of skin, forming blisters that do not heal. In some cases, these blisters can cover a large area of skin.
It is unclear what triggers the disease, although it appears that some people have a genetic susceptibility. Environmental agents may trigger the development of pemphigus in people who are likely to be affected by the disease because of their genes. In rare cases, it may be triggered by certain medications. In those cases, the disease usually goes away when the medication is stopped.