Purpura: Difference between revisions
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==Background==
==Background==
*Palpable [[petechiae]] and purpura are a result of either perivascular inflammation (vasculitis) or infection.
{{Skin anatomy background images}}
*Purpura results from extravasation of blood into the skin or mucous membranes
*Palpable purpura are a result of either perivascular inflammation (vasculitis) or infection
*Non-palpable petechiae usually occur in low platelet states such as [[ITP]] and [[DIC]]
*Non-palpable petechiae usually occur in low platelet states such as [[ITP]] and [[DIC]]
 
*Key EM distinction: palpable (vasculitis/infection) vs. non-palpable (thrombocytopenia/coagulopathy)
*Fever + purpura in a child is [[meningococcemia]] until proven otherwise — requires emergent antibiotics
{{Rash red flags}}
{{Rash red flags}}


==Clinical Features==
==Clinical Features==
''Both petechia and purpura do not blanch''
''Both petechiae and purpura do not blanch with pressure (distinguishing feature from erythema)''
*Purpura subdivided into:
*Purpura subdivided by size:
**<2mm of hemorrhage: petechiae  
**<2mm of hemorrhage: petechiae
**>2mm of hemorrhage: ecchymoses
**>2mm of hemorrhage: purpura
**Large areas: ecchymoses
*Palpable purpura: raised, can be felt; indicates vasculitis or septic emboli
*Non-palpable (flat) purpura: platelet disorder, coagulopathy, or fragile vessels
 
===Key Physical Exam Features===
*Distribution: dependent areas (gravitational), generalized, or localized
*Palpability: palpable vs. non-palpable
*Associated findings: fever, arthralgia, abdominal pain, renal involvement (Henoch-Schönlein purpura / IgA vasculitis)
*Mucosal involvement: oral petechiae, gingival bleeding (suggests severe thrombocytopenia)
*Signs of systemic illness: hemodynamic instability, altered mental status
{{Purpura rash images}}
 
===Red Flags===
*Fever + petechiae/purpura (meningococcemia, endocarditis, Rocky Mountain spotted fever)
*Rapidly spreading purpura (DIC, purpura fulminans)
*Platelets <10,000 (high risk of spontaneous bleeding)
*Active hemorrhage from mucosal sites
*Altered mental status with purpura (TTP — emergent plasma exchange)


==Differential Diagnosis==
==Differential Diagnosis==
{{Purpura DDX}}
{{Purpura DDX}}
{{Purpura DDX by findings}}
{{Purpura DDX by findings}}


==Evaluation==
==Evaluation==
*For children with fever and petechiae/purpura consider using the Barts Health NHS Trust guideline for workup. This guideline performed well head to head vs other guidelines in Petechiae in Children (PiC) study. <ref>Thomas et, al. Validating clinical practice guidelines for the management of children with non-blanching rashes in the UK (PiC): a prospective, multicentre cohort study, The Lancet Infectious Diseases, 2020, https://doi.org/10.1016/S1473-3099(20)30474-6</ref> <ref>Tessa Davis. Petechiae in Children – the PiC Study, Don't Forget the Bubbles, 2020. Available at: https://doi.org/10.31440/DFTB.30782</ref>
===All Patients===
[[File:Management of children with fever and non-blanching rash.png|thumb|Fever and non-blanching rash in children algorithm from Barts Health NHS Trust guideline. Original image from https://dontforgetthebubbles.com/petechiae-in-children-study/]]
*[[CBC]] with platelet count — most critical initial test
{{Purpura rash images}}
*Peripheral blood smear (schistocytes in TTP/HUS, blasts in leukemia)
*[[PT]]/[[INR]], [[PTT]] (coagulopathy assessment)
*[[BMP]] (renal function — assess for HUS, TTP)
 
===If Thrombocytopenic===
*Consider [[DIC]] panel: fibrinogen, D-dimer, fibrin degradation products
*[[LDH]], haptoglobin, reticulocyte count if concern for TTP/HUS
*Type and screen
*Consider blood cultures, [[lactate]] if febrile
 
===If Platelets Normal===
*Evaluate for coagulopathy (PT/INR, PTT)
*If palpable purpura: ESR, CRP, UA (renal involvement), complement levels (C3, C4)
*Consider skin biopsy referral (vasculitis workup)
*[[Blood cultures]], [[lactate]] if concern for septic emboli or endocarditis
 
===Pediatric===
*For children with fever and petechiae/purpura consider using the Barts Health NHS Trust guideline for workup, which performed well in the Petechiae in Children (PiC) study<ref>Thomas et al. Validating clinical practice guidelines for the management of children with non-blanching rashes in the UK (PiC): a prospective, multicentre cohort study, The Lancet Infectious Diseases, 2020, https://doi.org/10.1016/S1473-3099(20)30474-6</ref><ref>Tessa Davis. Petechiae in Children – the PiC Study, Don't Forget the Bubbles, 2020. Available at: https://doi.org/10.31440/DFTB.30782</ref>
[[File:Management of children with fever and non-blanching rash.png|thumb|Fever and non-blanching rash in children algorithm from Barts Health NHS Trust guideline.]]


==Management==
==Management==
*Management directed by underlying condition
===Emergent===
*'''Meningococcemia''': immediate IV [[ceftriaxone]] (do not delay for LP); fluid resuscitation
*DIC: treat underlying cause; transfuse platelets, FFP, cryoprecipitate as needed
*'''TTP''': emergent hematology consultation for plasma exchange; do NOT transfuse platelets (can worsen)
*Severe thrombocytopenia (<10,000) with active bleeding: platelet transfusion
 
===Condition-Specific===
*[[ITP]]: if bleeding or platelets <30,000: IV [[dexamethasone]], consider IVIG; hematology consultation
*[[Henoch-Schönlein purpura]] / IgA vasculitis: supportive care, NSAIDs for joint pain; monitor renal function
*Drug-induced thrombocytopenia: discontinue offending agent, supportive care
*[[HUS]]: supportive care, dialysis if needed; avoid antibiotics in typical (STEC) HUS
*Vasculitis: rheumatology consultation, may require immunosuppression


==Disposition==
==Disposition==
*Depends on underlying etiology
===Admit===
*Fever with petechiae/purpura and ill appearance
*Suspected meningococcemia, TTP, HUS, DIC
*Severe thrombocytopenia (<20,000) or active bleeding
*New diagnosis requiring urgent workup (possible leukemia, aplastic anemia)
*Hemodynamic instability
 
===Discharge===
*Well-appearing child with petechiae above the nipple line (mechanical cause — coughing, vomiting), normal CBC, and no fever
*Known stable ITP with platelet count at baseline and no bleeding
*Chronic/known vasculitis with mild flare — arrange outpatient follow-up
*Return precautions: fever, spreading rash, bleeding, altered mental status, worsening symptoms


==See Also==
==See Also==
*[[Rashes]]
*[[General approach to rashes]]
*[[ITP]]
*[[DIC]]
*[[TTP]]
*[[Henoch-Schönlein purpura]]
*[[Meningococcemia]]


==References==
==References==
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[[Category:Dermatology]]
[[Category:Dermatology]]
[[Category:Symptoms]]
[[Category:Symptoms]]
[[Category:Hematology]]

Latest revision as of 09:34, 22 March 2026

Background

Normal dermal anatomy.
  • Purpura results from extravasation of blood into the skin or mucous membranes
  • Palpable purpura are a result of either perivascular inflammation (vasculitis) or infection
  • Non-palpable petechiae usually occur in low platelet states such as ITP and DIC
  • Key EM distinction: palpable (vasculitis/infection) vs. non-palpable (thrombocytopenia/coagulopathy)
  • Fever + purpura in a child is meningococcemia until proven otherwise — requires emergent antibiotics

Rash Red Flags[1]

Clinical Features

Both petechiae and purpura do not blanch with pressure (distinguishing feature from erythema)

  • Purpura subdivided by size:
    • <2mm of hemorrhage: petechiae
    • >2mm of hemorrhage: purpura
    • Large areas: ecchymoses
  • Palpable purpura: raised, can be felt; indicates vasculitis or septic emboli
  • Non-palpable (flat) purpura: platelet disorder, coagulopathy, or fragile vessels

Key Physical Exam Features

  • Distribution: dependent areas (gravitational), generalized, or localized
  • Palpability: palpable vs. non-palpable
  • Associated findings: fever, arthralgia, abdominal pain, renal involvement (Henoch-Schönlein purpura / IgA vasculitis)
  • Mucosal involvement: oral petechiae, gingival bleeding (suggests severe thrombocytopenia)
  • Signs of systemic illness: hemodynamic instability, altered mental status

Purpural Rash

Red Flags

  • Fever + petechiae/purpura (meningococcemia, endocarditis, Rocky Mountain spotted fever)
  • Rapidly spreading purpura (DIC, purpura fulminans)
  • Platelets <10,000 (high risk of spontaneous bleeding)
  • Active hemorrhage from mucosal sites
  • Altered mental status with purpura (TTP — emergent plasma exchange)

Differential Diagnosis

Petechiae/Purpura (by cause)

Petechiae/Purpura (by findings)

Evaluation

All Patients

  • CBC with platelet count — most critical initial test
  • Peripheral blood smear (schistocytes in TTP/HUS, blasts in leukemia)
  • PT/INR, PTT (coagulopathy assessment)
  • BMP (renal function — assess for HUS, TTP)

If Thrombocytopenic

  • Consider DIC panel: fibrinogen, D-dimer, fibrin degradation products
  • LDH, haptoglobin, reticulocyte count if concern for TTP/HUS
  • Type and screen
  • Consider blood cultures, lactate if febrile

If Platelets Normal

  • Evaluate for coagulopathy (PT/INR, PTT)
  • If palpable purpura: ESR, CRP, UA (renal involvement), complement levels (C3, C4)
  • Consider skin biopsy referral (vasculitis workup)
  • Blood cultures, lactate if concern for septic emboli or endocarditis

Pediatric

  • For children with fever and petechiae/purpura consider using the Barts Health NHS Trust guideline for workup, which performed well in the Petechiae in Children (PiC) study[2][3]
Fever and non-blanching rash in children algorithm from Barts Health NHS Trust guideline.

Management

Emergent

  • Meningococcemia: immediate IV ceftriaxone (do not delay for LP); fluid resuscitation
  • DIC: treat underlying cause; transfuse platelets, FFP, cryoprecipitate as needed
  • TTP: emergent hematology consultation for plasma exchange; do NOT transfuse platelets (can worsen)
  • Severe thrombocytopenia (<10,000) with active bleeding: platelet transfusion

Condition-Specific

  • ITP: if bleeding or platelets <30,000: IV dexamethasone, consider IVIG; hematology consultation
  • Henoch-Schönlein purpura / IgA vasculitis: supportive care, NSAIDs for joint pain; monitor renal function
  • Drug-induced thrombocytopenia: discontinue offending agent, supportive care
  • HUS: supportive care, dialysis if needed; avoid antibiotics in typical (STEC) HUS
  • Vasculitis: rheumatology consultation, may require immunosuppression

Disposition

Admit

  • Fever with petechiae/purpura and ill appearance
  • Suspected meningococcemia, TTP, HUS, DIC
  • Severe thrombocytopenia (<20,000) or active bleeding
  • New diagnosis requiring urgent workup (possible leukemia, aplastic anemia)
  • Hemodynamic instability

Discharge

  • Well-appearing child with petechiae above the nipple line (mechanical cause — coughing, vomiting), normal CBC, and no fever
  • Known stable ITP with platelet count at baseline and no bleeding
  • Chronic/known vasculitis with mild flare — arrange outpatient follow-up
  • Return precautions: fever, spreading rash, bleeding, altered mental status, worsening symptoms

See Also

References

  1. ↑ Nguyen T and Freedman J. Dermatologic Emergencies: Diagnosing and Managing Life-Threatening Rashes. Emergency Medicine Practice. September 2002 volume 4 no 9.
  2. ↑ Thomas et al. Validating clinical practice guidelines for the management of children with non-blanching rashes in the UK (PiC): a prospective, multicentre cohort study, The Lancet Infectious Diseases, 2020, https://doi.org/10.1016/S1473-3099(20)30474-6
  3. ↑ Tessa Davis. Petechiae in Children – the PiC Study, Don't Forget the Bubbles, 2020. Available at: https://doi.org/10.31440/DFTB.30782
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