What is the disease of leg rash with joint pain?

▎The editors of WuXi AppTec's content team have skin allergies and rashes on the body are probably the more common symptoms in dermatology
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What if the legs are covered with rashes, and there are joint and abdominal pain? Recently, the team of Professor Chen Jianghua from the Renal Disease Center of the First Affiliated Hospital of Zhejiang University published a case in the British Medical Journal (BMJ), documenting and discussing the diagnosis and treatment of a long rash on both legs and other system discomforts
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Screenshot source: BMJ patient male and teenager
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Seeing a dermatologist due to a non-pruritic rash on the legs, pain in the abdomen and bilateral knee joints for a week
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Boy's statement: There was no history of upper respiratory tract infection within 4 weeks before the onset of symptoms
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Physical examination: purple-red papules can be palpable on both legs, extending from the ankle to the thigh (as shown in the picture below)
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The other inspection results were normal
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▲ Purpura can be touched on both legs
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(Image source: Reference [1]) The results of auxiliary blood and urine tests are as follows
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The stool occult blood test was positive, and the 24-hour urine protein quantitative index was higher than the normal value
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▲ Related blood and urine test results
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(Image source: Reference [1]) Diagnosis that can be ruled out due to auxiliary examination: meningococcal sepsis: because there are no biomarkers of fever, neurological symptoms and bacterial infection; thrombocytopenia: because the platelet count is within the normal range; coagulopathy : Because the blood coagulation biomarker level is within the normal range
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Because the rash is widely distributed and atypical, a skin biopsy of the papules is taken to distinguish between vasculitis, vascular disease, and embolism
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The biopsy revealed: Leukoblastic vasculitis
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As the patient's proteinuria level was abnormally high (2.
36g), a kidney biopsy sample was collected
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The biopsy showed that there were crescents around the capillaries and glomeruli, and lymphocytes and neutrophils were infiltrated (as shown in the figure below)
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Immunofluorescence staining of the biopsy sample showed that IgA was deposited in the venules behind the capillaries
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 ▲ Pathological examination of the kidney biopsy specimen showed a crescent shape (black circle); lymphocytes and neutrophils infiltrated the glomeruli around the capillaries (black arrow)
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(Image source: Reference [1]) Diagnosis of immunoglobulin A-related vasculitis (allergic purpura), treatment and follow-up, prednisone 40mg daily
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One week later, skin purpura, abdominal pain and joint pain were significantly improved
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Stool examination showed no red blood cells
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Routine urine examination after four weeks showed no hemorrhage cells and proteinuria
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The corticosteroid dose was gradually reduced, and the drug was discontinued after 4 months
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The patient was followed up by the nephrology department and urinalysis was performed once a month until the urine protein result was negative
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Case study points: When patients have symptoms of multiple organs (ie skin, kidney, joint, and gastrointestinal system symptoms), consider immunoglobulin A-related vasculitis
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Immunoglobulin A-related vasculitis is a systemic small vasculitis that mainly affects the skin, kidneys, gastrointestinal tract and joints; it can palpable purpura, kidney damage, arthralgia (80%) and abdominal pain (70%)
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It is characterized by the deposition of immunoglobulin A in the venules behind the capillaries, accompanied by fragmentation of white blood cells
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Purpura quickly develops from pink to red papules, which are distributed symmetrically, often on the legs and buttocks, and occasionally on the arms and trunk
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It is generally self-limiting and resolves within four weeks on average, and papules may evolve into bullous and necrotizing rashes
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The annual incidence rate for children is 326.
7 per 100,000, and the annual incidence rate for children aged 16 and above is 0.
8 per 100,000 to 1.
8 per 100,000
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Upper respiratory tract infections often appear one to two weeks before symptoms appear
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At least half of patients may have elevated serum immunoglobulin A levels
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A positive fecal occult blood test indicates that the gastrointestinal tract is involved
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The differential diagnosis excludes meningococcal sepsis, severe thrombocytopenia, and coagulopathy
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Purpura with renal damage is also seen in cryoglobulinemia vasculitis, systemic lupus erythematosus, Waldenstrom's macroglobulinemia, Wegener's granulomatosis, Churg-Strauss syndrome, microscopic polyangiitis and nodules Polyarteritis
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If the patient has severe proteinuria (>250mg/mmol), persistent moderate proteinuria (100~250mg/mmol) or impaired glomerular filtration rate
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Consider skin biopsy in cases of atypical rash to rule out other diagnoses
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Related reading: I have grown dozens of "birthmarks", and found out hereditary tumor susceptibility diseases? | Peking University Hospital team BMJ published a case of gingival ulcer for a month, but it was because of tumor! | NEJM Beijing Stomatological Hospital case suddenly went blind at the age of 45.
This high-risk infection is likely to target diabetic patients | Cases published in "The Lancet" of West China Hospital: Cases published in "The Lancet" of the First Affiliated Hospital of Zheng University: fever of unknown origin, genetic sequencing to identify infection reference materials[1] Song, Y.
, Zhou, Q.
, Qiao, J.
, & Chen, J.
(2021).
A boy with purpura on the legs.
bmj, 372.
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The opinions expressed in the article do not represent the position of WuXi AppTec, nor does it mean that WuXi AppTec supports or opposes the views in the article
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This article is not a treatment recommendation either
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If you need guidance on the treatment plan, please go to a regular hospital for treatment
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