see also:

• dermatology
• Fever with petechial or purpuric rash

• purpura is visible bleeding into the skin or mucous membranes which is non-blanching when pressure is applied

• petechiae - < 4mm spots
• macular purpura - non-palpable spots 4-10mm
  • many of the conditions which cause petechiae can progress to macular purpura
• macular ecchymoses - non-palpable spots larger than macular purpura
  • trauma / bruising
  • corticosteroids - easy bruising, thin skin
  • dependent purpura of legs due to venous hypertension
  • many of the conditions which cause petechiae can progress to ecchymoses
• palpable purpura - indicates underlying inflammation
  • usually vasculitis
    • Henoch-Schonlein purpura - children, mainly legs
    • urticarial vasculitis
    • drug-induced hypersensitivity vasculitis
      • steroids, sulphonamides, NSAIDs, thiazides, phenytoin, allopurinol, warfarin, and rarely, foods such as tatrazine additive
    • other causes of small vessel cutaneous vasculitis (adults, mainly legs)
      • infective endocarditis (including SBE)
      • Strept. pyogenes
      • HIV / AIDS
      • hepatitis B virus
      • hepatitis C virus
      • dengue fever
      • neoplasia / cancer / tumours
      • systemic lupus erythematosus (SLE)
      • rheumatoid arthritis
• retiform purpura - reticular patterned purpura
  • excludes:
    • livedo reticularis which is usually a functional response to cold as skin has zones of arterial predominance and zones of venous predominance between them
    • livido racemos

• increased venous pressure:
  • head - asphyxia / strangulation
  • upper trunk/face (superior vena cava distribution above the nipple line) - vomiting / severe coughing / etc
  • arms distal to BP cuff / tourniquet application
  • neonates due to delivery (NB. they can also have petechiae from acquired infection or maternal antiplatelet antibodies)
• thrombocytopenia
  • Idiopathic thrombocytopenic purpura (ITP)
  • other bone marrow disorders including leukaemia and aplastic anaemia
• early meningococcaemia
• other septicaemias eg. strept., Haemophilus influenzae type b
• scarlet fever
• viruses may cause petechiae such as:
  • dengue fever, erythema infectiosum, RMSF, parainfluenza, influenza, respiratory syncytial virus, enterovirus, rotavirus, atypical measles, rubella, yellow fever and adenovirus infections
• protozoal diseases (e.g., malaria and toxoplasmosis) and helminths (e.g., trichinellosis)
• drug reactions
• neck, shoulders, and especially the axillary folds in the upper chest area
  • fat embolism
• palmar and plantar petechiae
  • parvovirus B19 / hand, foot and mouth disease (often form small purpuric blisters - mainly in children)
• oropharyngeal palatial petechiae:
  • EBV / glandular fever / infectious mononucleosis
  • group A streptococcal pharyngitis
  • Arcanobacterium haemolyticum pharyngitis
  • rubella, roseola, viral haemorrhagic fevers, thrombocytopenia, and palatal trauma
• isolated to nail bed petechiae “splinter haemorrhages”:
  • nail trauma
  • septic emboli eg. infective endocarditis (including SBE)
• do not confuse with other lesions such as telangiectases and angiomas which will blanch when pressure of a glass slide is applied

• due to vessel wall damage (usually associated with inflammatory response):
  • infections:
    • meningococcaemia
    • Gram +ve sepsis (staph, strep)
    • ecthyma gangrenosum
    • angioinvasive fungal
    • strongyloidiasis
    • leprosy
  • vasculitis
    • IgA vasculitis
    • ANCA vasculitides
    • polyarteritis nodosa (PAN)
    • connective tissue (CT) disorders
    • cryoglobulinaemia type II/III
    • septic vasculitis
    • drug induced
  • depositional:
    • calciphylaxis
    • oxalosis
• vessel lumen occlusion (generally minimal inflammatory response around edges):
  • thrombotic
    • disseminated intravascular coagulation (DIC) / purpura fulminans
    • warfarin necrosis
    • hypercoagulable states
    • temperature related
    • platelet diasthesis
    • WBC occlusion - leukaemia
    • RBC occlusion
  • embolic
    • septic emboli
    • fat emboli
    • air emboli
    • cholesterol emboli

• ears:
  • levasimole
  • cryoglobulinaemia
• head:
  • angioinvasive fungi (mucomycosis, aspergillus)
• hands:
  • cholesterol emboli
  • endocarditis
  • DIC
  • essential thrombocythaemia
  • chilblains
  • purpura fulminans
  • cryoglobulinaemia
  • cryofibrinogenaemia
• feet:
  • as for hands but add:
    • small vessel vasculitis
    • hereditary coagulopathy
• trunk
  • strongyloidiasis
• trunk / lower limbs:
  • warfarin necrosis
  • heparin induced thrombocytopenia
  • ecthyma gangrenosum
  • purpura fulminans
  • leprosy
  • APLS
  • calciphylaxis