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IgA vasculitis (HSP), previously known as Henoch–Schönlein purpura, is an autoimmune disease that most commonly affects
child A child () is a human being between the stages of childbirth, birth and puberty, or between the Development of the human body, developmental period of infancy and puberty. The term may also refer to an unborn human being. In English-speaking ...
ren. In the skin, the disease causes palpable purpura (small, raised areas of bleeding underneath the skin), often with
joint pain Arthralgia () literally means 'joint pain'. Specifically, arthralgia is a symptom of injury, infection, illness (in particular arthritis), or an allergic reaction to medication Medication (also called medicament, medicine, pharmaceutic ...
and
abdominal pain Abdominal pain, also known as a stomach ache, is a symptom associated with both non-serious and serious medical issues. Since the abdomen contains most of the body's vital organs, it can be an indicator of a wide variety of diseases. Given th ...
. With
kidney In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...
involvement, there may be a loss of small amounts of
blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood is com ...
and
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
in the
urine Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...
(
hematuria Hematuria or haematuria is defined as the presence of blood or red blood cells in the urine. "Gross hematuria" occurs when urine appears red, brown, or tea-colored due to the presence of blood. Hematuria may also be subtle and only detectable with ...
and
proteinuria Proteinuria is the presence of excess proteins in the urine. In healthy persons, urine contains very little protein, less than 150 mg/day; an excess is suggestive of illness. Excess protein in the urine often causes the urine to become fo ...
), but this usually goes unnoticed; in a small proportion of cases, the kidney involvement proceeds to
chronic kidney disease Chronic kidney disease (CKD) is a type of long-term kidney disease, defined by the sustained presence of abnormal kidney function and/or abnormal kidney structure. To meet criteria for CKD, the abnormalities must be present for at least three mo ...
. HSP is often preceded by an
infection An infection is the invasion of tissue (biology), tissues by pathogens, their multiplication, and the reaction of host (biology), host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmis ...
, such as a throat infection. HSP is a systemic
vasculitis Vasculitis is a group of disorders that destroy blood vessels by inflammation. Both artery, arteries and veins are affected. Lymphangitis (inflammation of lymphatic vessels) is sometimes considered a type of vasculitis. Vasculitis is primarily c ...
(
inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...
of
blood vessel Blood vessels are the tubular structures of a circulatory system that transport blood throughout many Animal, animals’ bodies. Blood vessels transport blood cells, nutrients, and oxygen to most of the Tissue (biology), tissues of a Body (bi ...
s) and is characterized by deposition of
immune complex An immune complex, sometimes called an antigen-antibody complex or antigen-bound antibody, is a molecule formed from the binding of multiple antigens to antibodies. The bound antigen and antibody act as a unitary object, effectively an antigen of ...
es containing the antibody
immunoglobulin A Immunoglobulin A (IgA, also referred to as sIgA in its secretory form) is an antibody that plays a role in the immune function of mucous membranes. The amount of IgA produced in association with mucosal membranes is greater than all other ty ...
(IgA); the exact cause for this phenomenon is unknown. In children, it usually resolves within several weeks and requires no treatment apart from symptom control but may relapse in a third of cases and cause irreversible kidney damage in about one in a hundred cases. In adults, the prognosis is different from in children. The average duration of cutaneous lesions is 27.9 months. For many, it tends to be
relapsing–remitting Relapsing–remitting is a medical term referring to a presentation of disease symptoms that become worse over time ( relapsing), followed by periods of less severe symptoms that do not completely cease (partial remitting). The term is used to des ...
over a long period of time, rather than self-limiting and there tend to be more complications.


Signs and symptoms

Purpura Purpura () is a condition of red or purple discolored spots on the skin that do not blanch on applying pressure. The spots are caused by bleeding underneath the skin secondary to platelet disorders, vascular disorders, coagulation disorders, ...
,
arthritis Arthritis is a general medical term used to describe a disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, Joint effusion, swelling, and decreased range of motion of ...
, and
abdominal pain Abdominal pain, also known as a stomach ache, is a symptom associated with both non-serious and serious medical issues. Since the abdomen contains most of the body's vital organs, it can be an indicator of a wide variety of diseases. Given th ...
are known as the "classic triad" of Henoch–Schönlein purpura. Purpura occur in all cases, joint pains and arthritis in 80%, and abdominal pain in 62%. Some include gastrointestinal hemorrhage as a fourth criterion; this occurs in 33% of cases, sometimes, but not necessarily always, due to intussusception. The purpura typically appear on the legs and buttocks, but may also be seen on the arms, face and trunk. The abdominal pain is colicky in character, and may be accompanied by nausea, vomiting, constipation or diarrhea. There may be blood or mucus in the stools. The joints involved tend to be the
ankle The ankle, the talocrural region or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular joint. The ...
s,
knee In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the hu ...
s, and
elbow The elbow is the region between the upper arm and the forearm that surrounds the elbow joint. The elbow includes prominent landmarks such as the olecranon, the cubital fossa (also called the chelidon, or the elbow pit), and the lateral and t ...
s, but arthritis in the hands and feet is possible; the arthritis is nonerosive and hence causes no permanent deformity. Forty percent have evidence of
kidney In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...
involvement, mainly in the form of
hematuria Hematuria or haematuria is defined as the presence of blood or red blood cells in the urine. "Gross hematuria" occurs when urine appears red, brown, or tea-colored due to the presence of blood. Hematuria may also be subtle and only detectable with ...
(blood in the urine), but only a quarter will have this in sufficient quantities to be noticeable without laboratory tests. Problems in other organs, such as the
central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...
(brain and spinal cord) and
lung The lungs are the primary Organ (biology), organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the Vertebral column, backbone on either side of the heart. Their ...
s may occur, but is much less common than in the skin, bowel and kidneys. Of the 40% of patients who develop kidney involvement, almost all have evidence (visible or on
urinalysis Urinalysis, a portmanteau of the words ''urine'' and ''analysis'', is a Test panel, panel of medical tests that includes physical (macroscopic) examination of the urine, chemical evaluation using urine test strips, and #Microscopic examination, m ...
) of blood in the urine. More than half also have
proteinuria Proteinuria is the presence of excess proteins in the urine. In healthy persons, urine contains very little protein, less than 150 mg/day; an excess is suggestive of illness. Excess protein in the urine often causes the urine to become fo ...
(protein in the urine), which in one eighth is severe enough to cause
nephrotic syndrome Nephrotic syndrome is a collection of symptoms due to kidney damage. This includes proteinuria, protein in the urine, hypoalbuminemia, low blood albumin levels, hyperlipidemia, high blood lipids, and significant edema, swelling. Other symptoms ...
(generalised swelling due to low protein content of the blood). While abnormalities on urinalysis may continue for a long time, only 1% of all HSP patients develop
chronic kidney disease Chronic kidney disease (CKD) is a type of long-term kidney disease, defined by the sustained presence of abnormal kidney function and/or abnormal kidney structure. To meet criteria for CKD, the abnormalities must be present for at least three mo ...
.
Hypertension Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...
(high blood pressure) may occur. Protein loss and high blood pressure, as well as the features on
biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, an interventional radiologist, or an interventional cardiology, interventional cardiologist. The process involves the extraction of sampling (medicine), sample ...
of the kidney if performed, may predict progression to advanced kidney disease. Adults are more likely than children to develop advanced kidney disease.


Pathophysiology

Henoch–Schönlein purpura is a small-vessel vasculitis in which complexes of
immunoglobulin A Immunoglobulin A (IgA, also referred to as sIgA in its secretory form) is an antibody that plays a role in the immune function of mucous membranes. The amount of IgA produced in association with mucosal membranes is greater than all other ty ...
(IgA) and
complement component 3 Complement may refer to: The arts * Complement (music), an interval that, when added to another, spans an octave ** Aggregate complementation, the separation of pitch-class collections into complementary sets * Complementary color, in the vi ...
(C3) are deposited on arterioles, capillaries, and venules (hence it is a type III hypersensitivity reaction). The activation of the alternative complement pathway results in the deposition of IgA aggregates or IgA complexes in target organs (with deposition of C3). This leads to the production of inflammatory mediators, including vascular prostaglandins like prostacyclin, which may play a key role in the development of IgAV and its organ-specific clinical manifestations. As with
IgA nephropathy IgA nephropathy (IgAN), also known as Berger's disease () (and variations), or synpharyngitic glomerulonephritis, is a kidney disease, disease of the kidney (or nephropathy) and the immune system; specifically it is a form of glomerulonephritis o ...
, serum levels of IgA are high in HSP and there are identical findings on renal biopsy; however, IgA nephropathy has a predilection for young adults while HSP is more predominant among children. Further, IgA nephropathy typically only affects the kidneys while HSP is a systemic disease. HSP involves the skin and connective tissues, scrotum, joints, gastrointestinal tract and kidneys. The genetic basis remains unclear except for involvement of the human leukocyte antigen region of the genome. It is hypothesized to involve autoimmunity triggered by infections. Streptococcus strains and Parainfluenza virus are the most commonly associated pathogens, and in children Human Parvovirus B19 is a frequent viral trigger


Diagnosis

The diagnosis is based on the combination of the symptoms, as very few other diseases cause the same symptoms together.
Blood test A blood test is a medical laboratory, laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a hypodermic needle, or via fingerprick. Multiple tests for specific blood components, such as a glucose ...
s may show elevated
creatinine Creatinine (; ) is a breakdown product of creatine phosphate from muscle and protein metabolism. It is released at a constant rate by the body (depending on muscle mass). Biological relevance Serum creatinine (a blood measurement) is an impor ...
and
urea Urea, also called carbamide (because it is a diamide of carbonic acid), is an organic compound with chemical formula . This amide has two Amine, amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest am ...
levels (in kidney involvement), raised
IgA IGA or IgA may refer to: Businesses and organizations * IGA (supermarkets) (initially Independent Grocers Alliance), a name used by many independent supermarkets throughout the world ** IGA (Australian supermarket group), the local Australian v ...
levels (in about 50%), and raised
C-reactive protein C-reactive protein (CRP) is an annular (ring-shaped) pentameric protein found in blood plasma, whose circulating concentrations rise in response to inflammation. It is an acute-phase protein of hepatic origin that increases following interleukin ...
(CRP) or
erythrocyte sedimentation rate The erythrocyte sedimentation rate (ESR or sed rate) is the rate at which red blood cells in anticoagulated whole blood descend in a standardized tube over a period of one hour. It is a common hematology test, and is a non-specific measure of in ...
(ESR) results; none are specific for Henoch–Schönlein purpura. The
platelet Platelets or thrombocytes () are a part of blood whose function (along with the coagulation#Coagulation factors, coagulation factors) is to react to bleeding from blood vessel injury by clumping to form a thrombus, blood clot. Platelets have no ...
count may be raised, and distinguishes it from diseases where low platelets are the cause of the purpura, such as
idiopathic thrombocytopenic purpura Immune thrombocytopenic purpura (ITP), also known as idiopathic thrombocytopenic purpura or immune thrombocytopenia, is an Autoimmunity, autoimmune primary disorder of hemostasis characterized by a low platelet count in the absence of other cause ...
and
thrombotic thrombocytopenic purpura Thrombotic thrombocytopenic purpura (TTP) is a blood disorder that results in thrombi, blood clots forming in small blood vessels throughout the body. This results in a thrombocytopenia, low platelet count, hemolytic anemia, low red blood cells d ...
. If there is doubt about the cause of the skin lesions, a
biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, an interventional radiologist, or an interventional cardiology, interventional cardiologist. The process involves the extraction of sampling (medicine), sample ...
of the skin may be performed to distinguish the purpura from other diseases that cause it, such as
vasculitis Vasculitis is a group of disorders that destroy blood vessels by inflammation. Both artery, arteries and veins are affected. Lymphangitis (inflammation of lymphatic vessels) is sometimes considered a type of vasculitis. Vasculitis is primarily c ...
due to
cryoglobulinemia Cryoglobulinemia is a rare medical condition characterized by the presence of cryoglobulins in the blood. Cryoglobulins are abnormal proteins composed of immunoglobulins and sometimes complement components. Cryoglobulins specifically form g ...
; on microscopy, the appearances are of a hypersensitivity vasculitis, and
immunofluorescence Immunofluorescence (IF) is a light microscopy-based technique that allows detection and localization of a wide variety of target biomolecules within a cell or tissue at a quantitative level. The technique utilizes the binding specificity of anti ...
demonstrates IgA and C3 (a protein of the
complement system The complement system, also known as complement cascade, is a part of the humoral, innate immune system and enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promote inf ...
) in the blood vessel wall. However, overall serum complement levels are normal. On the basis of symptoms, it is possible to distinguish HSP from hypersensitivity vasculitis (HV). In a series comparing 85 HSP patients with 93 HV patients, five symptoms were found to be indicative of HSP: palpable purpura, abdominal angina, digestive tract hemorrhage (not due to intussussception), hematuria and age less than 20. The presence of three or more of these indicators has an 87% sensitivity for predicting HSP. Biopsy of the
kidney In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...
may be performed both to establish the diagnosis or to assess the severity of already suspected kidney disease. The main findings on kidney biopsy are increased cells and Ig deposition in the mesangium (part of the
glomerulus ''Glomerulus'' (; : glomeruli) is a common term used in anatomy to describe globular structures of entwined vessels, fibers, or neurons. ''Glomerulus'' is the diminutive of the Latin ''glomus'', meaning "ball of yarn". ''Glomerulus'' may refer to ...
, where blood is filtered),
white blood cell White blood cells (scientific name leukocytes), also called immune cells or immunocytes, are cells of the immune system that are involved in protecting the body against both infectious disease and foreign entities. White blood cells are genera ...
s, and the development of crescents. The changes are indistinguishable from those observed in
IgA nephropathy IgA nephropathy (IgAN), also known as Berger's disease () (and variations), or synpharyngitic glomerulonephritis, is a kidney disease, disease of the kidney (or nephropathy) and the immune system; specifically it is a form of glomerulonephritis o ...
. HSP can develop after infections with
streptococci ''Streptococcus'' is a genus of gram-positive spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs along a sing ...
( β-haemolytic, Lancefield group A),
hepatitis B Hepatitis B is an infectious disease caused by the '' hepatitis B virus'' (HBV) that affects the liver; it is a type of viral hepatitis. It can cause both acute and chronic infection. Many people have no symptoms during an initial infection. ...
,
herpes simplex virus Herpes simplex virus 1 and 2 (HSV-1 and HSV-2) are two members of the Herpesviridae#Human herpesvirus types, human ''Herpesviridae'' family, a set of viruses that produce Viral disease, viral infections in the majority of humans. Both HSV-1 a ...
,
parvovirus B19 Parvovirus B19, also called B19 virus (B19V), Human parvovirus B19, or sometimes erythrovirus B19, is a human virus in the family ''Parvoviridae'', genus ''Erythroparvovirus''. It measures only 23–26  nm in diameter. The virus is assigned ...
,
Coxsackievirus Coxsackieviruses are a few related enteroviruses that belong to the ''Picornaviridae'' family of viral envelope, nonenveloped, linear, positive-sense single-stranded RNA viruses, as well as its genus ''Enterovirus'', which also includes poliovi ...
,
adenovirus Adenoviruses (members of the family ''Adenoviridae'') are medium-sized (90–100 nm), nonenveloped (without an outer lipid bilayer) viruses with an icosahedral nucleocapsid containing a double-stranded DNA genome. Their name derives from t ...
, ''
Helicobacter pylori ''Helicobacter pylori'', previously known as ''Campylobacter pylori'', is a gram-negative, Flagellum#bacterial, flagellated, Bacterial cellular morphologies#Helical, helical bacterium. Mutants can have a rod or curved rod shape that exhibits l ...
'',
measles Measles (probably from Middle Dutch or Middle High German ''masel(e)'', meaning "blemish, blood blister") is a highly contagious, Vaccine-preventable diseases, vaccine-preventable infectious disease caused by Measles morbillivirus, measles v ...
,
mumps MUMPS ("Massachusetts General Hospital Utility Multi-Programming System"), or M, is an imperative, high-level programming language with an integrated transaction processing key–value database. It was originally developed at Massachusetts Gen ...
,
rubella Rubella, also known as German measles or three-day measles, is an infection caused by the rubella virus. This disease is often mild, with half of people not realizing that they are infected. A rash may start around two weeks after exposure and ...
, ''
Mycoplasma ''Mycoplasma'' is a genus of bacteria that, like the other members of the class ''Mollicutes'', lack a cell wall, and its peptidoglycan, around their cell membrane. The absence of peptidoglycan makes them naturally resistant to antibiotics ...
'' and numerous others. Drugs linked to HSP, usually as an idiosyncratic reaction, include the antibiotics
vancomycin Vancomycin is a glycopeptide antibiotic medication used to treat certain bacterial infections. It is administered intravenously ( injection into a vein) to treat complicated skin infections, bloodstream infections, endocarditis, bone an ...
and
cefuroxime Cefuroxime, sold under the brand name Zinacef among others, is a second-generation cephalosporin antibiotic used to treat and prevent a number of bacterial infections. These include pneumonia, meningitis, otitis media, sepsis, urinary tract inf ...
,
ACE inhibitor Angiotensin-converting-enzyme inhibitors (ACE inhibitors) are a class of medication used primarily for the treatment of high blood pressure and heart failure. This class of medicine works by causing relaxation of blood vessels as well as a decr ...
s
enalapril Enalapril, sold under the brand name Vasotec among others, is an ACE inhibitor medication used to treat high blood pressure, diabetic kidney disease, and heart failure. For heart failure, it is generally used with a diuretic, such as furosem ...
and
captopril Captopril, sold under the brand name Capoten among others, is an ACE inhibitor, angiotensin-converting enzyme (ACE) inhibitor used for the treatment of hypertension and some types of congestive heart failure. Captopril was the first oral ACE inh ...
, anti-inflammatory agent
diclofenac Diclofenac, sold under the brand name Voltaren among others, is a nonsteroidal anti-inflammatory drug (NSAID) used to treat pain and inflammatory diseases such as gout. It can be taken orally (swallowed by mouth), inserted rectally as a ...
, as well as
ranitidine Ranitidine, previously sold under the brand name Zantac among others, is a medication used to decrease stomach acid production. It was commonly used in treatment of peptic ulcer disease, gastroesophageal reflux disease, and Zollinger–Ellis ...
and
streptokinase Streptokinase is a thrombolysis, thrombolytic medication activating plasminogen by nonenzymatic mechanism. As a medication it is used to thrombolysis, break down clots in some cases of myocardial infarction (heart attack), pulmonary embolism, an ...
. Several diseases have been reported to be associated with HSP, often without a causative link. Only in about 35% of cases can HSP be traced to any of these causes. The exact cause of HSP is unknown, but most of its features are due to the deposition of abnormal antibodies in the wall of blood vessels, leading to
vasculitis Vasculitis is a group of disorders that destroy blood vessels by inflammation. Both artery, arteries and veins are affected. Lymphangitis (inflammation of lymphatic vessels) is sometimes considered a type of vasculitis. Vasculitis is primarily c ...
. These antibodies are of the subclass IgA1 in
polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...
s; it is uncertain whether the main cause is overproduction (in the digestive tract or the
bone marrow Bone marrow is a semi-solid biological tissue, tissue found within the Spongy bone, spongy (also known as cancellous) portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). It i ...
) or decreased removal of abnormal IgA from the circulation. It is suspected that abnormalities in the IgA1 molecule may provide an explanation for its abnormal behaviour in both HSP and the related condition
IgA nephropathy IgA nephropathy (IgAN), also known as Berger's disease () (and variations), or synpharyngitic glomerulonephritis, is a kidney disease, disease of the kidney (or nephropathy) and the immune system; specifically it is a form of glomerulonephritis o ...
. One of the characteristics of IgA1 (and IgD) is the presence of an 18
amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...
-long "hinge region" between
complement Complement may refer to: The arts * Complement (music), an interval that, when added to another, spans an octave ** Aggregate complementation, the separation of pitch-class collections into complementary sets * Complementary color, in the visu ...
-fixating regions 1 and 2. Of the amino acids, half is
proline Proline (symbol Pro or P) is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group but is rather a secondary amine. The secondary amine nitrogen is in the p ...
, while the others are mainly
serine Serine (symbol Ser or S) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated − form under biological conditions), a carboxyl group (which is in the deprotonated − ...
and
threonine Threonine (symbol Thr or T) is an amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH form when dissolved in water), a carboxyl group (which is in the deprotonated −COO− ...
. The majority of the serines and the threonines have elaborate sugar chains, connected through
oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
atoms ( O-glycosylation). This process is thought to stabilise the IgA molecule and make it less prone to
proteolysis Proteolysis is the breakdown of proteins into smaller polypeptides or amino acids. Protein degradation is a major regulatory mechanism of gene expression and contributes substantially to shaping mammalian proteomes. Uncatalysed, the hydrolysis o ...
. The first sugar is always N-acetyl-galactosamine (GalNAc), followed by other
galactose Galactose (, ''wikt:galacto-, galacto-'' + ''wikt:-ose#Suffix 2, -ose'', ), sometimes abbreviated Gal, is a monosaccharide sugar that is about as sweetness, sweet as glucose, and about 65% as sweet as sucrose. It is an aldohexose and a C-4 epime ...
s and
sialic acid Sialic acids are a class of alpha-keto acid sugars with a nine-carbon backbone. The term "sialic acid" () was first introduced by Swedish biochemist Gunnar Blix in 1952. The most common member of this group is ''N''-acetylneuraminic acid ...
. In HSP and IgAN, these sugar chains appear to be deficient. The exact reason for these abnormalities is not known.


Classification

Multiple standards exist for defining Henoch–Schönlein purpura, including the 1990
American College of Rheumatology The American College of Rheumatology (ACR; until 1985 called American Rheumatism Association) is an organization of and for physicians, health professionals, and scientists that advances rheumatology through programs of education, research, advocac ...
(ACR) classification and the 1994 Chapel Hill Consensus Conference (CHCC). Some have reported the ACR criteria to be more sensitive than those of the CHCC. More recent classifications, the 2006 European League Against Rheumatism (EULAR) and Pediatric Rheumatology Society (PReS) classification, include palpable purpura as a mandatory criterion, together with at least one of the following findings: diffuse abdominal pain, predominant IgA deposition (confirmed on skin biopsy), acute arthritis in any joint, and renal involvement (as evidenced by the presence of blood and/or protein in the urine).


Differential diagnosis

Henoch–Schönlein purpura may present with an atypical manifestation, which can be confused with papular urticaria,
systemic lupus erythematosus Lupus, formally called systemic lupus erythematosus (SLE), is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary among people and may be mild to severe. Common ...
, meningococcemia,
dermatitis herpetiformis Dermatitis herpetiformis (DH) is a chronic autoimmune blistering skin condition, characterised by intensely itchy blisters filled with a watery fluid. DH is a cutaneous manifestation of coeliac disease, although the exact causal mechanism is not ...
, and acute hemorrhagic edema of infancy.


Treatment

As of 2017, the optimal way to treat Henoch–Schönlein purpura remains controversial.
Analgesic An analgesic drug, also called simply an analgesic, antalgic, pain reliever, or painkiller, is any member of the group of drugs used for pain management. Analgesics are conceptually distinct from anesthetics, which temporarily reduce, and in s ...
s may be needed for the abdominal and joint pains.
Wound care The history of wound care spans from prehistory to modern medicine. Wounds naturally Wound healing, heal by themselves, but hunter-gatherers would have noticed several factors and certain herbalism, herbal remedies would speed up or assist the pro ...
is warranted if skin death and ulcerations occur. It is uncertain as to whether HSP needs treatment beyond controlling the symptoms. Most people do not receive therapy because of the high spontaneous recovery rate. Experts disagree on whether to routinely use
corticosteroids Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are invol ...
as treatment for HSP. However, if they are given early in the disease episode, the duration of symptoms may be shortened, and abdominal pain can improve significantly. Moreover, the chance of severe kidney problems may be reduced. A systematic review did not find any evidence that steroid treatment (
prednisone Prednisone is a glucocorticoid medication mostly used to immunosuppressive drug, suppress the immune system and decrease inflammation in conditions such as asthma, COPD, and rheumatologic diseases. It is also used to treat high blood calcium ...
) is effective at decreasing the likelihood of developing long-term kidney disease. Evidence of worsening kidney damage would normally prompt a kidney biopsy. Treatment may be indicated on the basis of the appearance of the biopsy sample; various treatments may be used, ranging from steroids by mouth to a combination of intravenous
methylprednisolone Methylprednisolone (Depo-Medrol, Medrol, Solu-Medrol) is a synthetic glucocorticoid, primarily prescribed for its anti-inflammatory and immunosuppressive effects. It is either used at low doses for chronic illnesses or used at high doses durin ...
(steroid),
cyclophosphamide Cyclophosphamide (CP), also known as cytophosphane among other names, is a medication used as chemotherapy and to suppress the immune system. As chemotherapy it is used to treat lymphoma, multiple myeloma, leukemia, ovarian cancer, breast cancer ...
and
dipyridamole Dipyridamole, sold under the brand name Persantine among others, is an antiplatelet drug of the nucleoside transport inhibitor and PDE3 inhibitor class that inhibits blood clot formation when given chronically and causes blood vessel dilatio ...
followed by prednisone. Other regimens include steroids/
azathioprine Azathioprine, sold under the brand name Imuran, among others, is an immunosuppressive medication. It is used for the treatment of rheumatoid arthritis, granulomatosis with polyangiitis, Crohn's disease, ulcerative colitis, and systemic lupus er ...
, and steroids/cyclophosphamide (with or without
heparin Heparin, also known as unfractionated heparin (UFH), is a medication and naturally occurring glycosaminoglycan. Heparin is a blood anticoagulant that increases the activity of antithrombin. It is used in the treatment of myocardial infarction, ...
and
warfarin Warfarin, sold under the brand name Coumadin among others. It is used as an anticoagulant, anticoagulant medication. It is commonly used to prevent deep vein thrombosis and pulmonary embolism, and to protect against stroke in people who ha ...
).
Intravenous immunoglobulin Immunoglobulin therapy is the use of a mixture of antibodies (normal human immunoglobulin) to treat several health conditions. These conditions include primary immunodeficiency, immune thrombocytopenic purpura, chronic inflammatory demyelinat ...
(IVIG) is occasionally used. There is no good evidence that treating children who have HSP with
antiplatelet An antiplatelet drug (antiaggregant), also known as a platelet agglutination inhibitor or platelet aggregation inhibitor, is a member of a class of pharmaceuticals that decrease platelet aggregation and inhibit thrombus formation. They are effectiv ...
agent prevents persistent kidney disease. There is also no evidence that treating children or adults with cyclophosphamide prevents severe kidney disease. Heparin treatment is not justified for people with HSP.


Prognosis

Overall prognosis is good in most patients, with one study showing recovery occurring in 94% and 89% of children and adults, respectively (some having needed treatment). In children under ten, the condition recurs in about a third of all cases, usually within the four months of the initial attack. Recurrence is more common in older children and adults.


Kidney involvement

In adults, kidney involvement progresses to
end-stage kidney disease Chronic kidney disease (CKD) is a type of long-term kidney disease, defined by the sustained presence of abnormal kidney function and/or abnormal kidney structure. To meet criteria for CKD, the abnormalities must be present for at least three m ...
(ESKD) more often than in children. In a UK series of 37 patients, 10 (27%) developed advanced kidney disease. Proteinuria, hypertension at presentation, and pathology features (crescentic changes, interstitial fibrosis and tubular atrophy) predicted progression. About 20% of children that exhibit nephrotic or nephritic features experience long permanent renal impairment. The findings on
renal biopsy Renal biopsy (also kidney biopsy) is a medical procedure in which a small piece of kidney is removed from the body for examination, usually under a microscope. Microscopic examination of the tissue can provide information needed to diagnose, moni ...
correlate with the severity of symptoms: those with asymptomatic hematuria may only have focal mesangial proliferation while those with proteinuria may have marked cellular proliferation or even crescent formation. The number of crescentic glomeruli is an important prognostic factor in determining whether the patient will develop chronic renal disease. In ESKD, some eventually need
hemodialysis Hemodialysis, American and British English spelling differences#ae and oe, also spelled haemodialysis, or simply ''"'dialysis'"'', is a process of filtering the blood of a person whose kidneys are not working normally. This type of Kidney dialys ...
or equivalent renal replacement therapy (RRT). If a
kidney transplant Kidney transplant or renal transplant is the organ transplant of a kidney into a patient with end-stage kidney disease (ESRD). Kidney transplant is typically classified as deceased-donor (formerly known as cadaveric) or living-donor transplantat ...
is found for a patient on RRT, the disease will recur in the graft (transplanted kidney) in about 35% of cases, and in 11%, the graft will fail completely (requiring resumption of the RRT and a further transplant).


Epidemiology

HSP occurs more often in children than in adults, and usually follows an
upper respiratory tract infection An upper respiratory tract infection (URTI) is an illness caused by an acute infection, which involves the upper respiratory tract, including the nose, sinuses, pharynx, larynx or trachea. This commonly includes nasal obstruction, sore throat ...
. Half of affected patients are below the age of six, and 90% are under ten. It occurs about twice as often in boys as in girls. The incidence of HSP in children is about 20 per 100,000 children per year, making it the most common vasculitis in children. Cases of HSP may occur anytime throughout the year, but some studies have found that fewer cases occur during the summer months.


History

The disease is named after Eduard Heinrich Henoch (1820–1910), a German pediatrician (nephew of
Moritz Heinrich Romberg Moritz Heinrich Romberg (11 November 1795 – 16 June 1873) was a German physician and neurologist who published a classic multi-volume textbook between 1840 and 1846. Considered a pioneer of neurology, he was the first to describe Romberg's sign ...
, the pioneer of neurology) and his teacher Johann Lukas Schönlein (1793–1864). Johann Schönlein described the condition as an entity in 1837; Eduard Heinrich Henoch in 1868 reported the first case of a patient with colic, bloody diarrhea, painful joints, and a rash. The English physician
William Heberden William Heberden FRS (13 August 171017 May 1801) was an English physician. Life He was born in London, where he received the early part of his education at St Saviour's Grammar School. Full text at Internet Archive (archive.org) At the end of ...
(1710–1801) and the dermatologist
Robert Willan __NOTOC__ Robert Willan (12 November 1757 near Sedbergh, Yorkshire, England – 7 April 1812 in Madeira, Portugal) was an English physician, and the founder of dermatology as a medical specialty. Life Willan was born on 12 November 1757 in Sed ...
(1757–1812) had already described the disease in 1802 and 1808, respectively, but the name ''Heberden–Willan disease'' has fallen into disuse. Moreover, Willan was the first to describe an exanthematous rash of childhood known as erythema infectiosum in 1799. In 1920, Eduard Glanzmann(1887-1959), a Swiss pediatrician noted for his contributions in the fields of infectious disease, vitamin therapy and, mostly the field of haematology. He recognised the role of allergy in the pathogenesis of Henoch–Schonlein purpura, hence the understanding of the allergic component in HSP.
William Osler Sir William Osler, 1st Baronet, (; July 12, 1849 – December 29, 1919) was a Canadian physician and one of the "Big Four" founding professors of Johns Hopkins Hospital. Osler created the first Residency (medicine), residency program for speci ...
is also the first to recognise the underlying
allergic Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic dermatitis, alle ...
mechanism of HSP. In 2012, the International Chapel Hill Consensus Conference Nomenclature of Vasculitides renamed HSP IgA vasculitis. Prior to this, the disease was more often known as Henoch–Schönlein purpura rather than the reverse.


In popular culture

The disease was featured in the TV series ''
House A house is a single-unit residential building. It may range in complexity from a rudimentary hut to a complex structure of wood, masonry, concrete or other material, outfitted with plumbing, electrical, and heating, ventilation, and air c ...
'' in the season 6 episode "Open and Shut".


See also

*
Cutaneous small-vessel vasculitis Cutaneous small-vessel vasculitis (CSVV) is inflammation of small blood vessels, usually accompanied by small lumps beneath the skin. The condition is also known as hypersensitivity vasculitis, cutaneous leukocytoclastic vasculitis, hypersensiti ...


References


External links

{{DEFAULTSORT:Henoch-Schonlein Purpura Rheumatology Pediatrics Nephrology Autoimmune diseases Ailments of unknown cause Vascular-related cutaneous conditions