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Bullous pemphigoid

Bullous pemphigoid

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Encyclopedia
Bullous pemphigoid, also referred to as BP, is an acute
Acute (medicine)
In medicine, an acute disease is a disease with either or both of:# a rapid onset, as in acute infection# a short course ....

 or chronic
Chronic (medicine)
A chronic disease is a disease or other human health condition that is persistent or long-lasting in nature. The term chronic is usually applied when the course of the disease lasts for more than three months. Common chronic diseases include asthma, cancer, diabetes and HIV/AIDS.In medicine, the...

 autoimmune skin disease, involving the formation of blisters, more appropriately known as bullae, at the space between the skin layers epidermis and dermis
Dermis
The dermis is a layer of skin between the epidermis and subcutaneous tissues, and is composed of two layers, the papillary and reticular dermis...

.

Signs and symptoms


Clinically the earliest lesion
Lesion
A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...

s may appear urticaria
Urticaria
Urticaria is a kind of skin rash notable for pale red, raised, itchy bumps. Hives is frequently caused by allergic reactions; however, there are many non-allergic causes...

l (like hives). Tense bullae eventually erupt, most commonly at the inner thighs and upper arms but the trunk and extremities are frequently both involved. Any part of the skin surface can be involved. Milia
Milia
A Milium , also called a milk spot or an oil seed, is a keratin-filled cyst that can appear just under the epidermis or on the roof of the mouth. Milia are commonly associated with newborn babies but can appear on people of all ages...

 are more common with epidermolysis bullosa acquisita
Epidermolysis bullosa acquisita
Epidermolysis bullosa acquisita is a chronic subepidermal blistering disease associated with autoimmunity to type VII collagen within anchoring fibril structures that are located at the dermal-epidermal junction....

 (EBA), because of the deeper antigenic targets. A more ring-like configuration, with a central depression or centrally collapsed bullae may indicate linear IgA disease
Linear IgA bullous dermatosis
Linear IgA bullous dermatosis is frequently associated with medication exposure, especially vancomycin, with men and women being equally affected. Linear IgA dermatosis is a rare immune-mediated blistering skin disease that may be divided into two types, chronic bullous disease of childhood and...

. The disease may be acute, but typically will wax and wane.

Pathophysiology


The bullae are formed by an immune reaction, initiated by the formation of IgG autoantibodies targeting the type XVII collagen
Collagen XVII
Collagen XVII, previously called BP180, is a transmembrane protein which plays a critical role in maintaining the linkage between the intracellular and the extracellular structural elements involved in epidermal adhesion .-Structure:...

 component of hemidesmosomes. It can also rarely involve the mucous membrane
Mucous membrane
The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...

s. Following antibody targeting, a cascade of immunomodulator
Immunomodulator
An immunomodulator, also known as an immunotherapy is a substance which has an effect on the immune system.- Immunosuppressants :Inhibits immune response in organ transplantation and autoimmune diseases.- Immunostimulants :...

s results in a variable surge of neutrophils
Neutrophil granulocyte
Neutrophil granulocytes are the most abundant type of white blood cells in mammals and form an essential part of the innate immune system. They are generally referred to as either neutrophils or polymorphonuclear neutrophils , and are subdivided into segmented neutrophils and banded neutrophils...

, lymphocyte
Lymphocyte
A lymphocyte is a type of white blood cell in the vertebrate immune system.Under the microscope, lymphocytes can be divided into large lymphocytes and small lymphocytes. Large granular lymphocytes include natural killer cells...

s and eosinophils
Eosinophil granulocyte
Eosinophil granulocytes, usually called eosinophils or eosinophiles , are white blood cells that are one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. Along with mast cells, they also control mechanisms associated with...

 coming to the affected area. Unclear events subsequently result in a separation along the dermal-epidermal junction and eventually stretch bullae.

Diagnosis


Diagnosis is based on two biopsies
Biopsy
A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...

 of the skin, one submitted for routine H&E stain
H&E stain
H&E stain, HE stain or hematoxylin and eosin stain is a popular staining method in histology. It is the most widely used stain in medical diagnosis; for example when a pathologist looks at a biopsy of a suspected cancer, the histological section is likely to be stained with H&E and termed H&E...

ing and one for immunofluorescence
Immunofluorescence
Immunofluorescence is a technique used for light microscopy with a fluorescence microscope and is used primarily on biological samples. This technique uses the specificity of antibodies to their antigen to target fluorescent dyes to specific biomolecule targets within a cell, and therefore allows...

 studies.

Treatment


Treatments include Class I topical steroids
Topical steroid
Topical steroids are the topical forms of corticosteroids. Topical steroids are the most commonly prescribed topical medications for the treatment of rash, eczema, and dermatitis. Topical steroids have anti-inflammatory properties, and are classified based on their vasoconstriction abilities. There...

  (clobetasol, halobetasol, etc.) which in some studies have proven to be equally as effective as systemic, or pill, therapy and somewhat safer. However, in difficult to manage or widespread cases, systemic prednisone
Prednisone
Prednisone is a synthetic corticosteroid drug that is particularly effective as an immunosuppressant drug. It is used to treat certain inflammatory diseases and some types of cancer, but has significant adverse effects...

 and powerful steroid-free immunosuppressant
Immunosuppressant
An immunosuppressant is any substance that performs immunosuppression of the immune system. They may be either exogenous, as immunosuppressive drugs, or endogenous, as ,e. g., testosterone...

 medications such as methotrexate
Methotrexate
Methotrexate , abbreviated MTX and formerly known as amethopterin, is an antimetabolite and antifolate drug. It is used in treatment of cancer, autoimmune diseases, ectopic pregnancy, and for the induction of medical abortions. It acts by inhibiting the metabolism of folic acid. Methotrexate...

, azathioprine
Azathioprine
Azathioprine is a purine analogue immunosuppressive drug. It is used to prevent organ rejection following organ transplantation and to treat a vast array of autoimmune diseases, including rheumatoid arthritis, pemphigus, inflammatory bowel disease , multiple sclerosis, autoimmune hepatitis, atopic...

 or mycophenolate mofetil
Mycophenolate mofetil
Mycophenolate mofetil is an immunosuppressant and prodrug of mycophenolic acid, used extensively in transplant medicine. It is a reversible inhibitor of inosine monophosphate dehydrogenase in purine biosynthesis, which is necessary for the growth of T cells and B cells...

 may be appropriate.

Epidemiology


Many mammals can be afflicted, including dog
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...

s, cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...

s, pig
Pig
A pig is any of the animals in the genus Sus, within the Suidae family of even-toed ungulates. Pigs include the domestic pig, its ancestor the wild boar, and several other wild relatives...

s, and horse
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...

s, as well as humans. Very rarely seen in children, it usually occurs in people 70 years of age and older. It is very rare in dogs; on average, three cases are diagnosed around the world each year.

At least one study indicates the incidence might be increasing in the United Kingdom.

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