Henoch–Schönlein purpura (HSP, also known as anaphylactoid purpura, [1] purpura rheumatica, [1] and Schönlein–Henoch purpura ) [1] is a disease of the skinand other organs that most commonly affects children. In the skin, the disease causes palpable purpura(small hemorrhages); often withointand abdominal pain. !ith kidneyin"ol"ement, there may be a loss of small amounts of blood and protein in the urine, but this usually goes unnoticed; in a small proportion of cases, the kidney in"ol"ement proceeds to chronic kidney disease. #$% is often preceded by an infection, such as a throat infection. #$% is a systemic "asculitis(inflammation of blood "essels) and is characteri&ed by deposition of immune comple'es containing the antibody Ig; the e'act cause for this phenomenon is unknown. It usually resol"es within se"eral weeks and reuires no treatment apart from symptom control, but may relapse in a third o f the cases and cause irre"ersible kidney da mage in about one in a hundred cases. Contents [hide] • 1 $igns and symptoms • * %athophysiology • + iagnosiso +.1 -lassification • /reatment • 0 %rognosiso 0.1 idney in"ol"ement • 2 3pidemiology • 4 #istory • 5 $ee also • 6 7eferences Signs and symptoms[edit]
Henoch–Schönlein purpura (HSP, also known as anaphylactoid purpura,[1] purpura
rheumatica,[1] and Schönlein–Henoch purpura)[1] is a disease of the skin and other organs that
most commonly affects children. In the skin, the disease causes palpable purpura (smallhemorrhages); often with oint and abdominal pain. !ith kidney in"ol"ement, there may be a
loss of small amounts of blood and protein in the urine, but this usually goes unnoticed; in asmall proportion of cases, the kidney in"ol"ement proceeds to chronic kidney disease. #$% is
often preceded by an infection, such as a throat infection.
#$% is a systemic "asculitis (inflammation of blood "essels) and is characteri&ed by deposition
of immune comple'es containing the antibody Ig; the e'act cause for this phenomenon is
unknown. It usually resol"es within se"eral weeks and reuires no treatment apart from symptomcontrol, but may relapse in a third of the cases and cause irre"ersible kidney damage in about one
8ore se"ere case of #$% on child9s foot, leg, and arm
%urpura, arthritis and abdominal pain are known as the :classic triad: of #enoch$ch<nlein
purpura.[*] %urpura occur in all cases, oint pains and arthritis in 5=>, and abdominal pain in
2*>. $ome include gastrointestinal hemorrhage as a fourth criterion; this occurs in ++> of cases,sometimes, but not necessarily always, due to intussusception.[+] /he purpura typically appear on
the legs and buttocks, but may also be seen on the arms, face and trunk. /he abdominal pain is
colicky in character, and may be accompanied by nausea, "omiting, constipation or diarrhea./here may be blood or mucus in the stools.[] /he oints in"ol"ed tend to be the ankles, knees,
and elbows, but arthritis in the hands and feet is possible; the arthritis is nonerosi"e and hence
causes no permanent deformity.[*] ?orty percent ha"e e"idence of kidney in"ol"ement, mainly inthe form of hematuria (blood in the urine), but only a uarter will ha"e this in sufficient
uantities to be noticeable without laboratory tests.[+] %roblems in other organs, such as the
central ner"ous system (brain and spinal cord) and lungs may occur, but is much less commonthan in the skin, bowel and kidneys.[0]
@f the => of patients who de"elop kidney in"ol"ement, almost all ha"e e"idence ("isible or on
urinalysis) of blood in the urine. 8ore than half also ha"e proteinuria (protein in the urine),
which in one eighth is se"ere enough to cause nephrotic syndrome (generalised swelling due tolow protein content of the blood). !hile abnormalities on urinalysis may continue for a long
time, only 1> of all #$% patients de"elop chronic kidney disease.[0] #ypertension (high blood
pressure) may occur. %rotein loss and high blood pressure, as well as the features on biopsy of
the kidney if performed, may predict progression to ad"anced kidney disease. dults are morelikely than children to de"elop ad"anced kidney disease.[0][2]
#enoch$ch<nlein purpura is a smallA"essel "asculitis in which comple'es of immunoglobulin
(Ig) and complement component + (-+) are deposited on arterioles, capillaries, and "enules. s
with Ig nephropathy, serum le"els of Ig are high in #$% and there are identical findings onrenal biopsy; howe"er, Ig nephropathy has a predilection for young adults while #$% is more
predominant among children. ?urther, Ig nephropathy typically only affects the kidneys while
#$% is a systemic disease. #$% in"ol"es the skin and connecti"e tissues, scrotum, oints,gastrointestinal tract and kidneys.[4]
Diagnosis[edit]
Immunostaining showing Ig in the glomerulus of a patient with #enochA$ch<nlein nephritis
/he diagnosis is based on the combination of the symptoms, as "ery few other diseases cause the
same symptoms together. Blood tests may show ele"ated creatinine and urea le"els (in kidney
in"ol"ement), raised Ig le"els (in about 0=>[4]), and raised -Areacti"e protein (-7%) orerythrocyte sedimentation rate (3$7) results; none are specific for #enoch$ch<nlein purpura.
/he platelet count may be raised, and distinguishes it from diseases where low platelets are the
cause of the purpura, such as idiopathic thrombocytopenic purpura and thrombotic
thrombocytopenic purpura.[*]
If there is doubt about the cause of the skin lesions, a biopsy of the skin may be performed to
distinguish the purpura from other diseases that cause it, such as "asculitis due to
cryoglobulinemia; on microscopy the appearances are of a hypersensiti"ity "asculitis, andimmunofluorescence demonstrates Ig and -+ (a protein of the complement system) in the
blood "essel wall.[*] #owe"er, o"erall serum complement le"els are normal.
@n the basis of symptoms, it is possible to distinguish #$% from hypersensiti"ity "asculitis
(#C). In a series comparing 50 #$% patients with 6+ #C patients, fi"e symptoms were found to be indicati"e of #$%D palpable purpura, abdominal angina, digesti"e tract hemorrhage (not due to
intussussception), hematuria and age less than *=. /he presence of three or more of theseindicators has an 54> sensiti"ity for predicting #$%.[5]
Biopsy of the kidney may be performed both to establish the diagnosis or to assess the se"erity
of already suspected kidney disease. /he 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 de"elopment of crescents. /he changes are indistinguishable from those obser"edin Ig nephropathy.[4]
measles, mumps, rubella, Mycoplasma and numerous others.
[4]
rugs linked to #$%, usually as anidiosyncratic reaction, include the antibiotics "ancomycin and cefuro'ime, -3 inhibitors enalapril and captopril, antiAinflammatory agent diclofenac, as well as ranitidine and
streptokinase. $e"eral diseases ha"e been reported to be associated with #$%, often without a
causati"e link. @nly in about +0> of cases can #$% be traced to any of these causes.[4]
/he e'act cause of #$% is unknown, but most of its features are due to the deposition of
abnormal antibodies in the wall of blood "essels, leading to "asculitis. /hese antibodies are of
the subclass Ig1 in polymers; it is uncertain whether the main cause is o"erproduction (in the
digesti"e tract or the bone marrow) or decreased remo"al of abnormal Ig from the circulation.[4] It is suspected that abnormalities in the Ig1 molecule may pro"ide an e'planation for its
abnormal beha"iour in both #$% and the related condition Ig nephropathy. @ne of the
characteristics of Ig1 (and Ig) is the presence of an 15 amino acidAlong :hinge region: between complementAfi'ating regions 1 and *. @f the amino acids, half is proline, while the
others are mainly serine and threonine. /he maority of the serines and the threonines ha"e
elaborate sugar chains, connected through o'ygen atoms (@Aglycosylation). /his process isthought to stabilise the Ig molecule and make it less prone to proteolysis. /he first sugar is
always GAacetylAgalactosamine (HalGc), followed by other galactoses and sialic acid. In #$%
and IgG, these sugar chains appear to be deficient. /he e'act reason for these abnormalities is
not known.[0][4]
Classification[edit]
8ultiple standards e'ist for defining #enoch$ch<nlein purpura, including the 166= merican-ollege of 7heumatology (-7) classification[6][1=] and the 166 -hapel #ill -onsensus
-onference (-#--).[11] $ome ha"e reported the -7 criteria to be more sensiti"e than those of
the -#--.[1*]
8ore recent classifications, the *==2 3uropean Feague gainst 7heumatism (3F7) and%ediatric 7heumatology $ociety (%7e$) classification, include palpable purpura as a mandatory
criterion, together with at least one of the following findingsD diffuse abdominal pain,
predominant Ig deposition (confirmed on skin biopsy), acute arthritis in any oint, and renal
in"ol"ement (as e"idenced by the presence of blood andJor protein in the urine).[1+]
Treatment[edit]
nalgesics may be needed for the abdominal and oint pains. It is uncertain as to whether #$%
needs treatment beyond controlling the symptoms. 8ost patients do not recei"e therapy because
of the high spontaneous reco"ery rate. $teroids are generally a"oided.[0] #owe"er, if they aregi"en early in the disease episode, the duration of symptoms may be shortened, and abdominal
pain can impro"e significantly. 8oreo"er, the chance of se"ere kidney problems may be reduced.[1] #owe"er, some e"idence suggests that steroids do not decrease the likelihood of de"elopinglongAterm kidney disease.[10]
3"idence of worsening kidney damage would normally prompt a kidney biopsy. /reatment may
be indicated on the basis of the appearance of the biopsy sample; "arious treatments may be
used, ranging from oral steroids to a combination of intra"enous methylprednisolone (steroid),cyclophosphamide and dipyridamole followed by prednisone. @ther regimens include
steroidsJa&athioprine, and steroidsJcyclophosphamide (with or without heparin and warfarin).
Intra"enous immunoglobulin (ICIH) is occasionally used.[4]
Prognosis[edit]
@"erall prognosis is good in most patients, with one study showing reco"ery occurring in 6>
and 56> of children and adults, respecti"ely (some ha"ing needed treatment). [12] 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 .[+]
7ecurrence is more common in older children and adults.[0]
Kidney involvement[edit]
In adults, kidney in"ol"ement progresses to endAstage renal disease (3$7) more often than inchildren. In a series of +4 patients, 1= (*4>) de"eloped ad"anced kidney disease.
%roteinuria, hypertension at presentation, and pathology features (crescentic changes, interstitial
fibrosis and tubular atrophy) predicted progression.[2] bout *=> of children that e'hibitnephrotic or nephritic features e'perience long permanent renal impairment. [14]
/he findings on renal biopsy correlate with the se"erity of symptomsD those with asymptomatic
hematuria may only ha"e focal mesangial proliferation while those with proteinuria may ha"emarked cellular proliferation or e"en crescent formation. /he number of crescentic glomeruli isan important prognostic factor in determining whether the patient will de"elop chronic renal
disease.[0]
In 3$7, some e"entually need hemodialysis or eui"alent renal replacement therapy (77/). If
a kidney transplant is found for a patient on 77/, the disease will recur in the graft (transplanted
kidney) in about +0> of cases, and in 11>, the graft will fail completely (reuiring resumption
of the 77/ and a further transplant).[4]
pidemiology[edit]
#$% occurs more often in children than in adults,[12] and usually follows an upper respiratory tractinfection. #alf of affected patients are below the age of si', and 6=> are under ten. It occurs
about twice as often in boys as in girls.[0] /he incidence of #$% in children is about *= per
1==,=== children per year, making it the most common "asculitis in children.[15]
-ases of #$% may occur anytime throughout the year, but some studies ha"e found that fewer
cases occur during the summer months.[16]
History[edit]
/he disease is named after 3duard #einrich #enoch (15*=161=), a Herman pediatrician (nephew of 8orit& #einrich 7omberg) and his teacher Kohann Fukas $ch<nlein (146+152),
who described it in the 152=s. $ch<nlein associated the purpura and arthritis, and #enoch the
purpura and gastrointestinal in"ol"ement. /he 3nglish physician !illiam #eberden (141=15=1)and the dermatologist 7obert !illan (1404151*) had already described the disease in 15=* and
15=5, respecti"ely, but the name Heberden–Willan disease has fallen into disuse. !illiam @sler
was the first to recognise the underlying allergic mechanism of #$%.[*=]
