HEMATOLOGY-ONCOLOGY
DISORDERS OF HEMOSTASIS
Figure 5-3 Approach to abnormal hemostasis
Figure 5-4 Coagulation Cascade
Purpura (nonblanching purple/red lesions due to extravasation of RBCs into dermis)
• Nonpalpable (macular; ≤3 mm in diameter = petechiae; >3 mm = ecchymoses)
platelet disorder: thrombocytopenia, defect in platelet fxn
thromboemboli: DIC, TTP, cholesterol or fat emboli
trauma or vascular fragility: amyloidosis, Ehlers-Danlos, scurvy
• Palpable (papular); vasculitis: leukocytoclastic, HSP, PAN, RMSF;
infectious emboli: meningococcemia, bacterial endocarditis
• Purpura fulminans (aka retiform purpura): purpura + hypotension + DIC; typically due to infxn/sepsis, protein C or S deficiency or APS (see section on DIC)