Henoch–Schönlein purpura, also known as allergic purpura or anaphylactoid purpura and commonly abbreviated to HSP, is a systemic vasculitis Both arteries and veins are affected. Lymphangitis is sometimes considered a type of vasculitis (inflammation of blood vessels) characterized by deposition of immune complexes An immune complex is the combination of an epitope with an antibody directed against that epitope. The bound antigen and the binding antibody are referred to as a single entity in this state containing the antibody IgA Immunoglobulin A is an antibody playing a critical role in mucosal immunity. More IgA is produced in mucosal linings than all other types of antibody combined; between 3 and 5g is secreted into the intestinal lumen each day.. However, sources are correct when they indicate immunoglobulin G as the most common form of immunoglobulin in the human in the skin The skin is the outer covering of the body. In humans, it is the largest organ of the integumentary system made up of multiple layers of epithelial tissues, and guards the underlying muscles, bones, ligaments and internal organs. Skin of a different nature exists in amphibians, reptiles, birds. Human skin is not unlike that of most other mammals and kidney The kidneys are paired organs seen in many types of animals, including vertebrates and some invertebrates. Part of the urinary system, they are responsible for urine production as well as a number of other homeostatic functions. These include regulation of electrolytes, acid-base balance, and blood pressure; excretion of wastes such as urea and. It occurs mainly in young children.
Typical symptoms include palpable purpura Purpura is the appearance of red or purple discolorations on the skin that do not blanch on applying pressure. They are caused by bleeding underneath the skin. Purpura measure 0.3-1 cm, whereas petechiae measure less than 3 mm, and ecchymoses greater than 1 cm (small hemorrhages in the skin), joint pains Diagnosis involves interviewing the patient and performing physical exams. When attempting to establish the cause of the arthralgia, the emphasis is on the interview . The patient is asked questions intended to narrow the number of potential causes. Given the varied nature of these possible causes, some questions may seem irrelevant. For example, and abdominal pain Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem. Most frequently the cause is benign and/or self-limited, but more serious causes may. Most cases are self-limiting and require no treatment apart from symptom control, but the disease may relapse in a third of the cases and cause irreversible kidney damage in about one in a hundred cases.[1] The exact cause of Henoch-Schönlein purpura is unknown, although it may occur after certain viral and bacterial infections, as well as an adverse drug reaction An adverse drug reaction is an expression that describes harm associated with the use of given medications at a normal dose. The meaning of this expression differs from the meaning of "side effect", as this last expression might also imply that the effects can be beneficial. The study of ADRs is the concern of the field known as to some medications.
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Classification
Multiple standards exist for defining Henoch-Schönlein purpura. These include the 1990 American College of Rheumatology (ACR) classification[2][3] and the 1994 Chapel Hill Consensus Conference (CHCC).[4] Some have reported the ACR criteria to be more sensitive Sensitivity and specificity are statistical measures of the performance of a binary classification test. The sensitivity measures the proportion of actual positives which are correctly identified as such (e.g. the percentage of sick people who are identified as having the condition); and the specificity measures the proportion of negatives which than those of the CHCC.[5]
A more recent classification is the 2006 European League Against Rheumatism (EULAR) and Pediatric Rheumatology Society (PReS) classification. These 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 hematuria and/or proteinuria).[6]
Signs and symptoms
Presentation
More severe case of HSP on child's foot, leg, and armPurpura Purpura is the appearance of red or purple discolorations on the skin that do not blanch on applying pressure. They are caused by bleeding underneath the skin. Purpura measure 0.3-1 cm, whereas petechiae measure less than 3 mm, and ecchymoses greater than 1 cm, arthritis There are different forms of arthritis and each has a different cause. The most common form of arthritis, osteoarthritis is a result of trauma to the joint, infection of the joint, or age. Other arthritis forms are rheumatoid arthritis and psoriatic arthritis, autoimmune diseases in which the body attacks itself. Septic arthritis is caused by and abdominal pain Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem. Most frequently the cause is benign and/or self-limited, but more serious causes may are known as the classic triad of Henoch-Schönlein purpura.[7] Purpura occur in all cases, joint pains and arthritis in 80%, and abdominal pain in 62%. Some include gastrointestinal hemorrhage Gastrointestinal bleeding or gastrointestinal hemorrhage describes every form of hemorrhage in the gastrointestinal tract, from the pharynx to the rectum. It has diverse causes, and a medical history, as well as physical examination, generally distinguishes between the main forms. The degree of bleeding can range from nearly undetectable to acute, as a fourth criterion; this occurs in 33% of cases, sometimes but not necessarily due to intussusception An intussusception is a medical condition in which a part of the small intestine has in-vaginated into another section of intestine, similar to the way in which the parts of a collapsible telescope slide into one another. The part which prolapses into the other is called the intussusceptum, and the part which receives it is called the.[8] 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.[9] The joints involved tend to be the ankles In human anatomy, the ankle joint is formed where the foot and the leg meet. The ankle, or talocrural joint, is a synovial hinge joint that connects the distal ends of the tibia and fibula in the lower limb with the proximal end of the talus bone in the foot. The articulation between the tibia and the talus bears more weight than between the, knees The knee joint joins the thigh with the leg and consists of two articulations: one between the femur and tibia, and one between the femur and patella. It is the largest and most complicated joint in the human body. The knee is a mobile trocho-ginglymus , which permits flexion and extension as well as a slight medial and lateral rotation. Since in, and elbows The elbow is the region surrounding the elbow-joint—the ginglymus or hinge joint in the middle of the arm. Three bones form the elbow joint: the humerus of the upper arm, and the paired radius and ulna of the forearm but arthritis in the hands and feet is possible; the arthritis is non-erosive and hence causes no permanent deformity.[7] Forty percent have evidence of kidney The kidneys are paired organs seen in many types of animals, including vertebrates and some invertebrates. Part of the urinary system, they are responsible for urine production as well as a number of other homeostatic functions. These include regulation of electrolytes, acid-base balance, and blood pressure; excretion of wastes such as urea and involvement, mainly in the form of hematuria In medicine, hematuria, or haematuria, is the presence of red blood cells in the urine. It can be a sign that there is a kidney stone or a tumor in the urinary tract (kidneys, ureters, urinary bladder, prostate, and urethra), ranging from trivial to lethal. If white blood cells are found in addition to red blood cells, then it is a signal of (blood in the urine), but only a quarter will have this in sufficient quantities to be noticeable without laboratory tests.[8] Problems in other organs, such as the central nervous system The central nervous system is the part of the nervous system that functions to coordinate the activity of all parts of the bodies of multicellular organisms. In vertebrates, the central nervous system is enclosed in the meninges. It contains the majority of the nervous system and consists of the brain and the spinal cord. Together with the (brain and spinal cord) and lungs The lung or pulmonary system is the essential respiration organ in air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located in the chest on either side of the heart. Their principal function is to transport oxygen from the atmosphere into the bloodstream, may occur, but much less commonly than the skin, bowel and kidneys.[1]
The disease tends to last about 4 weeks, and then resolves spontaneously.[1]
Kidney involvement
Of the 40% of patients who develop kidney involvement, almost all have evidence (visible or on urinalysis A urinalysis is an array of tests performed on urine and one of the most common methods of medical diagnosis. A part of a urinalysis can be performed by using urine dipsticks, in which the test results can be read as color changes) of blood in the urine. More than half also have proteinuria Proteinuria (/prəʊtiː'nʊəriə/, from protein and urine) means the presence of an excess of serum proteins in the urine. The protein in the urine often causes the urine to become foamy, although foamy urine may also be caused by bilirubin in the urine (bilirubinuria), retrograde ejaculation, pneumaturia (air bubbles in the urine) due to a (protein in the urine), which in one eighth is severe enough to cause nephrotic syndrome Nephrotic syndrome is a nonspecific disorder in which the kidneys are damaged, causing them to leak large amounts of protein from the blood into the urine (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 , also known as chronic renal disease, is a progressive loss of renal function over a period of months or years. The symptoms of worsening kidney function are unspecific, and might include feeling generally unwell and experiencing a reduced appetite. Often, chronic kidney disease is diagnosed as a result of screening of.[1] Hypertension Hypertension, also referred to as high blood pressure, HTN or HPN, is a medical condition in which the blood pressure is chronically elevated. In current usage, the word "hypertension" without a qualifier normally refers to systemic, arterial hypertension. The other type is pulmonary hypertension and involves lung circulation (high blood pressure) may occur. Protein loss and high blood pressure, as well as the features on biopsy A biopsy is a medical test involving the removal of cells or tissues for examination. It is the 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. When an entire lump or suspicious area is removed, the of the kidney if performed, may predict progression to advanced kidney disease. Adults are more likely than children to develop advanced kidney disease.[1][10]
Diagnosis
Immunostaining Immunohistochemistry or IHC refers to the process of localizing proteins in cells of a tissue section exploiting the principle of antibodies binding specifically to antigens in biological tissues. It takes its name from the roots "immuno," in reference to antibodies used in the procedure, and "histo," meaning tissue showing IgA in the glomerulus A glomerulus is a capillary tuft surrounded by Bowman's capsule in nephrons of the vertebrate kidney. It receives its blood supply from an afferent arteriole of the renal circulation. Unlike most other capillary beds, the glomerulus drains into an efferent arteriole rather than a venule. The resistance of the arterioles results in high pressure in of a patient with Henoch-Schönlein nephritis Nephritis is inflammation of the kidney. The word comes from the Greek nephro- meaning "of the kidney" and -itis meaning "inflammation". Nephritis is often caused by infections, toxins, and auto-immune diseases.The diagnosis is based on the combination of the symptoms, as very few other diseases cause the same symptoms together. Blood tests A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a needle, or via fingerprick may show elevated creatinine Creatinine is a break-down product of creatine phosphate in muscle, and is usually produced at a fairly constant rate by the body (depending on muscle mass). Chemically, creatinine is a spontaneously formed cyclic derivative of creatine. Creatinine is chiefly filtered out of the blood by the kidneys, though a small amount is actively secreted by and urea Urea or carbamide is an organic compound with the chemical formula (N levels (in kidney involvement), raised IgA Immunoglobulin A is an antibody playing a critical role in mucosal immunity. More IgA is produced in mucosal linings than all other types of antibody combined; between 3 and 5g is secreted into the intestinal lumen each day.. However, sources are correct when they indicate immunoglobulin G as the most common form of immunoglobulin in the human levels (in about 50%[11]), and raised C-reactive protein C-reactive protein is a protein found in the blood, the levels of which rise in response to inflammation (an acute-phase protein) (CRP) or erythrocyte sedimentation rate The erythrocyte sedimentation rate , also called a sedimentation rate or Biernacki Reaction, is the rate at which red blood cells precipitate in a period of 1 hour. It is a common haematology test which is a non-specific measure of inflammation. To perform the test, anticoagulated blood is placed in an upright tube, known as a Westergren tube and (ESR) results; none are specific for Henoch-Schönlein purpura. The platelet Platelets, or thrombocytes, are small, irregularly-shaped anuclear cells, 2-4 µm in diameter, which are derived from fragmentation of precursor megakaryocytes. The average lifespan of a platelet is between 8 and 12 days. Platelets play a fundamental role in hemostasis and are a natural source of growth factors. They circulate in the blood of count may be raised, and distinguishes it from diseases where low platelets are the cause of the purpura, such as idiopathic thrombocytopenic purpura Idiopathic thrombocytopenic purpura is the condition of having a low platelet count (thrombocytopenia) of no known cause (idiopathic). As most causes appear to be related to antibodies against platelets, ITP is also known as immune thrombocytopenic purpura or immune-mediated thrombocytopenic purpura. Often ITP is asymptomatic, however a very low and thrombotic thrombocytopenic purpura Thrombotic thrombocytopenic purpura is a rare disorder of the blood-coagulation system, causing extensive microscopic thromboses to form in small blood vessels throughout the body (thrombotic microangiopathy). Most cases of TTP arise from inhibition of the enzyme ADAMTS13, a metalloprotease responsible for cleaving large multimers of von.[7]
If there is doubt about the cause of the skin lesions, a biopsy A biopsy is a medical test involving the removal of cells or tissues for examination. It is the 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. When an entire lump or suspicious area is removed, the of the skin may be performed to distinguish the purpura from other diseases that cause purpura, such as vasculitis Both arteries and veins are affected. Lymphangitis is sometimes considered a type of vasculitis due to cryoglobulinemia; on microscopy the appearances are of a hypersensitivity vasculitis Hypersensitivity vasculitis is a small vessel vasculitis, usually due to a hypersensitivity reaction and immunofluorescence Immunofluorescence is the labeling of antibodies or antigens with fluorescent dyes. This technique is often used to visualize the subcellular distribution of biomolecules of interest. Immunofluorescent-labeled tissue sections or cultures are studied using a fluorescence microscope or by confocal microscopy demonstrates IgA and C3 Complement component 3, often simply called C3, is a protein of the immune system. It plays a central role in the complement system and contributes to innate immunity. In humans it is encoded on chromosome 19 by a gene called C3 (a protein of the complement system The complement system is a biochemical cascade that helps clear pathogens from an organism. It is part of the larger immune system that is not adaptable and does not change over the course of an individual's lifetime; as such it belongs to the innate immune system. However, it can be recruited and brought into action by the adaptive immune system) in the blood vessel wall.[7]
On the basis of symptoms, it is possible to distinguish HSP from hypersensitivity vasculitis Hypersensitivity vasculitis is a small vessel vasculitis, usually due to a hypersensitivity reaction (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 Abdominal angina is postprandial abdominal pain that occurs in individuals with insufficient blood flow to meet mesenteric visceral demands. The term angina is used in reference to angina pectoris, a similar symptom due to obstruction of the coronary artery. The American Heritage Stedman's Medical Dictionary defines abdominal angina as ", 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 Sensitivity and specificity are statistical measures of the performance of a binary classification test. The sensitivity measures the proportion of actual positives which are correctly identified as such (e.g. the percentage of sick people who are identified as having the condition); and the specificity measures the proportion of negatives which for predicting HSP.[12]
Biopsy of the kidney The kidneys are paired organs seen in many types of animals, including vertebrates and some invertebrates. Part of the urinary system, they are responsible for urine production as well as a number of other homeostatic functions. These include regulation of electrolytes, acid-base balance, and blood pressure; excretion of wastes such as urea and 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, where blood is filtered), white blood cells, and the development of crescents. The changes are indistinguishable from those observed in IgA nephropathy.[11]
Pathophysiology
Microphotograph of a histological section of human skin prepared for direct immunofluorescence using an anti-IgA antibody. The skin is a biopsy of a patient with Henoch-Schonlein purpura. IgA deposits are found in the walls of small superficial capillaries (yellow arrows). The pale wavy green area on top is the epidermis, the bottom fibrous area is the dermis.HSP can develop after infections with streptococci (β-haemolytic, Lancefield group A), hepatitis B, herpes simplex virus, parvovirus B19, Coxsackievirus, adenovirus, Helicobacter pylori,[1] measles, mumps, rubella, mycoplasma and numerous others.[11] Drugs linked to HSP, usually as an idiosyncratic reaction, include the antibiotics vancomycin and cefuroxime, ACE inhibitors enalapril and captopril, anti-inflammatory agent diclofenac, as well as ranitidine and streptokinase.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.[11]
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. These antibodies are of the subclass IgA1 in polymers; it is uncertain whether the main cause is overproduction (in the digestive tract or the bone marrow) or decreased removal of abnormal IgA from the circulation.[11] 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. One of the characteristics of IgA1 (and IgD) is the presence of an 18 amino acid-long hinge region between complement-fixating region 1 and 2. Of the amino acids, half is proline, while the other ones are mainly serine and threonine. The majority of the serines and the threonines have elaborate sugar chains, connected through oxygen atoms (O-glycosylation). This process is thought to stabilise the IgA molecule and make it less prone to proteolysis. The first sugar is always N-acetyl-galactosamine (GalNAc), followed by other galactoses and sialic acid. In HSP and IgAN, it appears that these sugar chains are deficient. The exact reason for these abnormalities is not known.[1][11]
Treatment
Pain killers may be needed for the abdominal pain and joint pains. It is uncertain as to whether HSP needs treatment beyond controlling the symptoms. Most patients do not receive therapy because of the high spontaneous recovery rate. Steroids are generally avoided.[1] 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 is reduced.[13]
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 oral steroids to a combination of intravenous methylprednisolone (a potent steroid), cyclophosphamide and dipyridamole followed by prednisone. Other regimens include steroids/azathioprine, and steroids/cyclophosphamide (with or without heparin and warfarin). Intravenous immunoglobulin (IVIG) is occasionally used.[11]
Prognosis
Recovery and recurrence
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).[14]
In children under ten, the condition recurs in about a third of all cases and usually within the first four months after the initial attack.[8] Recurrence is more common in older children and adults.[1]
Kidney involvement
In adults, kidney involvement progresses to end-stage renal disease (ESRD) more often. 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.[10]
The findings on renal biopsy 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.[1]
In end-stage renal disease, some eventually need hemodialysis or equivalent renal replacement therapy (RRT). If a kidney transplant is found for a patient on RRT, there is a risk of about 35% over 5 years that the disease will recur in the graft (transplanted kidney), and 11% that the graft will fail completely (requiring resumption of the RRT and a further transplant).[11]
Epidemiology
HSP occurs more often in children than in adults, and usually follows an upper respiratory tract infection. Half of affected patients are below the age of six, and 90% under ten. It occurs more often in boys than in girls (about twice as often).[1]
The incidence of HSP in children is about 20 per 100,000 children per year; this makes it the most common vasculitis in childhood.[15]
History
The disease is eponymously named after Eduard Heinrich Henoch (1820-1910), a German pediatrician, and his teacher Johann Lukas Schönlein (1793-1864), who described it in the 1860s. However the English physician William Heberden (1710-1801) and the dermatologist Robert Willan (1757-1812) had already described the disease in 1802 and 1808, respectively, but the name Heberden-Willan disease has fallen into disuse. William Osler was the first to recognise the underlying allergic mechanism of HSP.[16]
See also
References
- ^ a b c d e f g h i j k Saulsbury FT (2001). "Henoch-Schönlein purpura". Curr Opin Rheumatol 13 (1): 35–40. doi:10.1097/00002281-200101000-00006. PMID 11148713.
- ^ Mills JA, Michel BA, Bloch DA, et al. (1990). "The American College of Rheumatology 1990 criteria for the classification of Henoch-Schönlein purpura". Arthritis Rheum. 33 (8): 1114–21. PMID 2202310.
- ^ "1990 criteria for the classification of Henoch-Schönlein purpura". http://www.rheumatology.org/publications/classification/hsp.asp. Retrieved on 2007-12-15.
- ^ Jennette JC, Falk RJ, Andrassy K, et al. (1994). "Nomenclature of systemic vasculitides. Proposal of an international consensus conference". Arthritis Rheum. 37 (2): 187–92. doi:10.1002/art.1780370206. PMID 8129773.
- ^ Murali NS, George R, John GT, et al. (2002). "Problems of classification of Henoch Schonlein purpura: an Indian perspective". Clin. Exp. Dermatol. 27 (4): 260–3. doi:10.1046/j.1365-2230.2002.01063.x. PMID 12139664.
- ^ Ozen S, Ruperto N, Dillon MJ, et al. (July 2006). "EULAR/PReS endorsed consensus criteria for the classification of childhood vasculitides". Ann. Rheum. Dis. 65 (7): 936–41. doi:10.1136/ard.2005.046300. PMID 16322081. http://ard.bmj.com/cgi/content/full/65/7/936.
- ^ a b c d Kraft DM, Mckee D, Scott C (1998). "Henoch-Schönlein purpura: a review". Am Fam Physician 58 (2): 405–8, 411. PMID 9713395. http://www.aafp.org/afp/980800ap/kraft.html.
- ^ a b c Saulsbury FT (1999). "Henoch-Schönlein purpura in children. Report of 100 patients and review of the literature". Medicine (Baltimore) 78 (6): 395–409. doi:10.1097/00005792-199911000-00005. PMID 10575422.
- ^ Fauci AS (1987). "269:The Vasculitis Syndromes". in Braunwald E, Isselbacher KJ, Petersdorf RG, Wilson JD, Martin JB, Fauci AS. Harrison's Book of Internal Medicine. 2 (11th ed.). McGraw Hill. pp. 1441. ISBN 0-07-079454-5.
- ^ a b Shrestha S, Sumingan N, Tan J, et al. (2006). "Henoch Schönlein purpura with nephritis in adults: adverse prognostic indicators in a UK population". QJM 99 (4): 253–65. doi:10.1093/qjmed/hcl034. PMID 16565522. http://qjmed.oxfordjournals.org/cgi/content/full/99/4/253.
- ^ a b c d e f g h Rai A, Nast C, Adler S (01 Dec 1999). "Henoch-Schönlein purpura nephritis". J. Am. Soc. Nephrol. 10 (12): 2637–44. PMID 10589705. http://jasn.asnjournals.org/cgi/content/full/10/12/2637.
- ^ Michel BA, Hunder GG, Bloch DA, Calabrese LH (1992). "Hypersensitivity vasculitis and Henoch-Schönlein purpura: a comparison between the 2 disorders". J. Rheumatol. 19 (5): 721–8. PMID 1613701.
- ^ Weiss PF, Feinstein JA, Luan X, Burnham JM, Feudtner C (2007). "Effects of corticosteroid on Henoch-Schönlein purpura: a systematic review". Pediatrics 120 (5): 1079–87. doi:10.1542/peds.2007-0667. PMID 17974746.
- ^ Blanco R, Martínez-Taboada VM, Rodríguez-Valverde V, García-Fuentes M, González-Gay MA (1997). "Henoch-Schönlein purpura in adulthood and childhood: two different expressions of the same syndrome". Arthritis Rheum. 40 (5): 859–64. doi:10.1002/art.1780400513. PMID 9153547.
- ^ Gardner-Medwin JM, Dolezalova P, Cummins C, Southwood TR (2002). "Incidence of Henoch-Schönlein purpura, Kawasaki disease, and rare vasculitides in children of different ethnic origins". Lancet 360 (9341): 1197–202. doi:10.1016/S0140-6736(02)11279-7. PMID 12401245.
- ^ Schönlein-Henoch purpura at Who Named It?
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Categories: Hematology | Rheumatology | Pediatrics | Nephrology | Autoimmune diseases | Ailments of unknown etiology | Vascular-related cutaneous conditions
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