Purpura - Differential Diagnosis Framework



Non-blanchable, dark red to purple, hemorrhagic skin lesions that result from leakage of RBC's secondary to platelet disorders, vascular disorders, coagulation disorders, or other causes.



Etiology:

 • Vascular occlusion

 • Disruptions in vascular integrity/inflammation

 • Thrombocytopenia

 • Platelet defects

 • Coagulation disorders



CAUSES OF NON-PALPABLE PURPURA:

Platelet Defects/Quantity:

 • Primary Causes:

	- Thrombocytopenia: ITP

 • Secondary Causes:

	- Drug induced

 	- Bone marrow disease

 	- DIC/TTP/HUS

 	- Hemolytic anemia

 	- Splenomegaly

 	- CTD (SLE)

 	- Viral infections

 	- Hemangiomas: 

	- Kasabach-Merritt syndrome

Coagulation Defects:

 • DIC, TTP/HUS

 • Anticoagulants (Warfarin necrosis)

 • VIT K deficiency

 • Liver disease

 • Hemophilia

 • Von Willebrand disease (VWD)

 • Hypercoagulable States:

	- Livedo reticularis

	- Retiform purpura

 	- Protein C/S deficiencies

 	- PNH

 	- APLS

 • Acute Infectious Purpura Fulminans (DIC Features Present):

	- Neisseria meningitidis

	- Varicella

 	- Group A Streptococcus

 	- Streptococcus pneumoniae

Vascular Fragility:

 • Decreased Support Of Dermal Vessels:

	- Amyloidosis

 	- Corticosteroids

 	- Vitamin C/Scurvy

 	- Actinic damage

 	- Solar purpura

 	- Trauma

 • Collagen Disorders: Ehlers-Danlos

 • Pigmented Purpuric Dermatosis: Schamberg Disease

Others:

 • Fat emboli

 • Cholesterol emboli

 • Septic emboli

 • Gardner-Diamond syndrome



CAUSES OF PALPABLE PURPURA:

Vasculitis:

 • Hypersensitivity/Leukocytoclastic vasculitis

 • Ig A vasculitis/HSP

 • Cryoglobulinemia (MIXED)

 • ANCA associated small vessel vasculitis

	- GPA

	- EGPA

	- MPA

 • CTD Associated

	- SLE, Sjogren's.

 • HCV, HBV

Not Vasculitis:

 • Meningiococcemia

 • Gonococcemia

 • Rocky mountain spotted fever

 • Drug reactions

 • Erythema gangrenosum

 • Bacterial endocarditis

 • Liveoid Vasculopathy



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