What causes petechiae?

Causes of Petechiae

Petechiae are primarily caused by bleeding disorders, infections, medications, trauma, or vascular integrity issues, with the specific etiology requiring thorough investigation to guide appropriate management. 1

Primary Causes of Petechiae

1. Bleeding Disorders

• Platelet Disorders:

  • Thrombocytopenia (low platelet count <150,000/μL)
  • Immune thrombocytopenic purpura (ITP)
  • Thrombotic thrombocytopenic purpura (TTP)
  • Platelet function disorders 2, 1

• Coagulation Factor Deficiencies:

  • Hemophilia (factor VIII or IX deficiency)
  • Von Willebrand disease (not reliably detected by PT/PTT)
  • Factor XIII deficiency
  • Fibrinogen abnormalities 2

2. Infectious Causes

• Bacterial Infections:

  • Meningococcal infection (rapidly progressing rash)
  • Rocky Mountain Spotted Fever (typically begins 2-4 days after fever onset)
  • Group A streptococcal infections
  • Disseminated gonococcal infection 2, 1

• Viral Infections:

  • Enteroviral infections
  • Epstein-Barr virus
  • Cytomegalovirus
  • Parvovirus B19
  • Human herpesvirus 6 (roseola) 2, 1

• Other Infectious Causes:

  • Ehrlichiosis and anaplasmosis (often with leukopenia and thrombocytopenia)
  • Leptospirosis
  • Mycoplasma pneumoniae infection 2

3. Medication-Induced

• Anticoagulants and fibrinolytic therapy (can cause vasculitis-like reaction)
• Certain antibiotics
• Immune checkpoint inhibitors
• Various medications affecting platelet function or production 1, 3

4. Trauma and Mechanical Causes

• Increased pressure (tourniquet phenomenon)
• Vigorous coughing or vomiting (causing facial or oral petechiae)
• Cardiopulmonary resuscitation
• Localized pressure in infants (e.g., from diapers) 4, 5, 6

5. Vascular Integrity Issues

• Vasculitis
• Scurvy (vitamin C deficiency)
• Amyloidosis
• Senile purpura (age-related capillary fragility)
• Ehlers-Danlos syndrome 1, 4

6. Other Causes

• Hemorrhagic transformation of ischemic stroke
• Kawasaki disease
• Toxic-shock syndrome
• Stevens-Johnson syndrome
• Acute hemorrhagic edema of infancy 2, 1

Distribution Patterns and Diagnostic Significance

• Localized petechiae: Often benign, especially in well-appearing infants without fever

  • Lower extremities: Common in infants due to mechanical causes 5
  • Oral/facial: May occur after vomiting, coughing, or crying 4

• Generalized petechiae: More concerning, especially with:

  • Fever (consider sepsis, meningococcemia)
  • Rapidly progressing rash
  • Systemic symptoms 1

• Palms and soles: Classically associated with RMSF but can occur in other conditions 2

Key Diagnostic Considerations

1. Initial Laboratory Evaluation:

   • Complete blood count with peripheral smear
   • Coagulation studies (PT/INR, PTT)
   • Inflammatory markers (CRP, ESR)
   • Liver and kidney function tests 1

2. Additional Testing Based on Clinical Suspicion:

   • Blood cultures (if infection suspected)
   • Specific serologies or PCR for tick-borne illnesses
   • ADAMTS13 activity (if TTP suspected)
   • Bone marrow examination (if indicated by blood counts) 1

Important Clinical Pitfalls

• Do not delay treatment in suspected sepsis or meningococcemia while awaiting laboratory confirmation
• Medication review is essential as many drugs can cause petechiae
• Up to 20% of RMSF cases may have absent or atypical rash
• Localized petechiae in well-appearing infants are usually benign and may not require extensive workup
• Any skin sloughing, blistering, or mucosal involvement requires emergency dermatology referral 1

Petechiae represent a symptom rather than a disease, and identifying the underlying cause is crucial for effective management and treatment of the primary condition.