Purpura

Basics

Description

  • Skin lesions caused by extravasation of blood into the skin or subcutaneous tissue
  • Can be caused by fragile capillaries, poor dermal support, and/or platelet dysfunction
  • The resultant lesions do not blanch completely with pressure (as seen when pressing down through a glass slide)
  • Classification by size and pattern:
    • Petechiae (≤4 mm)
    • Purpuric lesions (5–10 mm)
    • Ecchymoses (>10 mm)
    • Reticulate (Net-like or branching pattern)
  • Color determined by depth and time of onset:
    • Red if superficial and recent onset
    • Purple if deep
    • Deep purple, brown, orange, or blue–green with later presentations
  • Localized purpura is often due to local trauma, pressure effects, or regional vascular abnormalities
  • Nonpalpable purpura:
    • Caused by platelet dysfunction or coagulation defects leading to hemorrhage without vessel wall inflammation
    • Platelet disorders or coagulation factor result in impaired hemostasis and spontaneous bleeding
    • Microvascular occlusion can cause ischemic purpura, often reticulate when thrombosis is involved
    • Endothelial support dysfunction due to platelet abnormalities leads to blood leakage into the skin without inflammation
  • Palpable purpura:
    • Caused by leading to vessel wall inflammation and blood leakage
    • Immune complex deposition and complement activation trigger neutrophilic damage, resulting in vessel necrosis and hemorrhage
    • Direct endothelial injury (septic vasculitis, angioinvasive fungi, embolic disease) can cause thrombotic or infectious vascular destruction
  • Overlapping presentations:
    • Disseminated intravascular coagulation (DIC) can present as reticulate palpable purpura (thrombotic phase) or diffuse petechiae/ecchymoses (coagulopathic phase)
    • Cryoglobulinemia can cause reticulate nonpalpable purpura (vascular occlusion) or palpable purpura (vasculitis driven)
    • Meningococcemia and Rocky Mountain Spotted fever initially present with nonpalpable petechiae but progress to palpable necrotic purpura

Etiology

Nonpalpable Purpura

  • Petechiae and purpura (2–10 mm)
    • Viral:
      • Echovirus
      • Coxsackie
      • Measles
      • Parvovirus B19
      • Dengue
    • Drugs:
      • Acetaminophen
      • Allopurinol
      • Anticoagulants
      • Aspirin
      • Corticosteroids
      • Digoxin
      • Furosemide
      • Gold salts
      • Lidocaine
      • Methyldopa
      • Nonsteroidal antiinflammatory drugs
      • Penicillin G
      • Phenylbutazone
      • Quinidine
      • Quinine
      • Rifampin
      • Steroids
      • Sulfonamides
      • Thiazides
    • Nutritional deficiencies:
      • Vitamin K deficiency
      • Vitamin C deficiency (scurvy)
    • Hematologic disorders:
      • Idiopathic thrombocytopenic purpura (ITP)
      • Thrombotic thrombocytopenic purpura (TTP)
      • Hemolytic uremic syndrome (HUS)
      • DIC
      • Thrombocytopenia (<50,000 plt/cc)
      • Thrombocytosis (>1,000,000 plt/cc)
      • Essential thrombocythemia
      • Paroxysmal nocturnal hemoglobinuria
    • Vascular causes:
      • Abrupt spiking elevations of intravascular pressure (childbirth, vomiting, paroxysmal coughing)
      • Hemophilia A/B (factor VIII/IX deficiency)
      • Von Willebrand disease
      • Solar purpura
      • Posttransfusion purpura
      • Ehlers–Danlos syndrome
  • Ecchymoses (>10 mm, bruises):
    • Trauma
    • Coagulation disorders:
      • Hemophilia
      • Von Willebrand disease
      • Liver disease
    • Senile purpura (age-related capillary fragility)
    • Corticosteroid-induced skin atrophy
    • Waldenström macroglobulinemia
  • Nonpalpable reticulate purpura:
    • Livedo reticularis
    • Livedo racemosa
    • Noninflammatory thrombotic occlusion (cholesterol emboli, cryofibrinogenemia, hypercoagulable states)
    • Protein C or S deficiency

Palpable Purpura

  • Nodular or diffuse palpable purpura:
    • Viral:
      • Epstein–Barr virus
      • Cytomegalovirus
      • Hepatitis B
    • Bacterial:
      • Streptococcus
      • Gonococcus
      • Meningococcus
      • Pseudomonas
      • Rickettsia rickettsii (Rocky Mountain spotted fever)
    • Drugs:
      • Allopurinol
      • Anti-influenza vaccines
      • Cephalosporins
      • Gold
      • Heparin
      • Hydralazine
      • Iodides
      • Levamisole
      • Metoclopramide
      • Penicillin G
      • Phenylbutazone
      • Phenytoin
      • Quinidine
      • Quinine
      • Streptomycin
      • Sulfonamides
      • Thiazides
      • Ticlopidine
    • Vasculitides and autoimmune conditions:
      • Leukocytoclastic vasculitis (LCV)
      • Henoch–Schönlein purpura (IgA vasculitis)
      • Cryoglobulinemic vasculitis (hepatitis C-associated, autoimmune diseases)
      • Rheumatoid vasculitis
      • Sjögren syndrome
      • Lupus
      • Granulomatosis with polyangiitis (Wegener granulomatosis)
    • Malignancies:
      • Leukemia
      • Lymphoma
      • Solid tumors with paraneoplastic vasculitis
  • Reticulate palpable purpura:
    • Medium-vessel vasculitis:
      • Polyarteritis nodosa
      • ANCA-associated vasculitis
      • IgA vasculitis
    • Thrombotic disorders:
      • Antiphospholipid syndrome
      • Heparin-induced thrombocytopenia
      • DIC with widespread thrombosis in medium-to-small vessels
    • Fungal and parasitic infections (generally immunocompromised hosts)
      • Candida
      • Aspergillus
      • Strongyloides hyperinfection syndrome
      • Mucormycosis
    • Calciphylaxis (vascular calcification and thrombosis)

Pediatric Considerations

  • Henoch–Schönlein purpura
  • HUS
  • Kawasaki disease
  • Malignancy/bone marrow failure
  • Neonatal:
    • Extramedullary erythropoiesis in rubella and cytomegalovirus (blueberry muffin baby)
    • Purpura fulminans (protein C and S deficiency)
    • Maternal ITP
    • Wiskott–Aldrich syndrome
    • Kasabach–Merritt syndrome

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