What is the work-up and management of purpura?

Work-up and Management of Purpura

Initial Diagnostic Approach

The diagnosis of purpura begins with a complete blood count with platelet count and peripheral blood smear examination to distinguish thrombocytopenic from non-thrombocytopenic causes, which fundamentally determines the subsequent management pathway. 1

Essential First-Line Tests

• Complete blood count (CBC) with platelet count is the fundamental first test for any patient presenting with purpura 1, 2
• Peripheral blood smear examination must be performed to confirm true thrombocytopenia, assess platelet morphology, and exclude pseudothrombocytopenia, leukemia, or other hematologic disorders 3, 1
• Prothrombin time (PT) and activated partial thromboplastin time (aPTT) should be obtained to evaluate for coagulation factor deficiencies 2

Critical Clinical Assessment

• Assess for systemic involvement immediately to exclude life-threatening conditions like meningococcemia, Rocky Mountain Spotted Fever (5-10% case-fatality if untreated), or purpura fulminans requiring urgent intervention 4, 5
• Examine for skin tenderness, pain, and Nikolsky sign to identify Stevens-Johnson syndrome/toxic epidermal necrolysis, which requires immediate drug discontinuation and specialized care 4, 6
• Document body surface area (BSA) involvement as >30% BSA suggests severe disease requiring aggressive management 6
• Check for mucosal involvement (eyes, mouth, genitalia) as erosive hemorrhagic mucositis indicates SJS/TEN 6

Conditional Testing Based on Clinical Context

When Thrombocytopenia is Present (Platelet Count <150,000)

• HIV antibody testing should be performed in patients with risk factors for HIV infection 3, 1
• Abdominal CT or ultrasound is appropriate only if splenomegaly is suspected on physical examination 3, 1
• Bone marrow aspiration should be performed in patients with persistent thrombocytopenia lasting >6-12 months or those unresponsive to IVIg, but is not required before initiating initial therapy 3

When Vasculitis or Systemic Disease is Suspected

• Urinalysis with microscopy to assess for glomerulonephritis in Henoch-Schönlein purpura (look for proteinuria, RBC casts, dysmorphic RBCs) 4
• Antiphospholipid antibodies and ADAMTS13 activity if thrombotic microangiopathy is suspected in lupus patients 3
• Skin biopsy should not be delayed while awaiting laboratory results, as histopathology is crucial for definitive diagnosis of vasculitis, pigmented purpuric dermatosis, or drug reactions 6

In Pregnant Women

• Blood pressure measurement and liver function tests must be performed to rule out preeclampsia as an alternative diagnosis 3, 1

Management Algorithm

For Immune Thrombocytopenic Purpura (ITP)

Children with ITP

• Platelet count >30,000 with asymptomatic or minor purpura only: No hospitalization or treatment required; observation is appropriate 3, 1
• Platelet count <20,000 with significant mucous membrane bleeding OR <10,000 with minor purpura: Treat with IVIg or glucocorticoids 3, 1
• Severe, life-threatening bleeding: Hospitalize immediately and administer high-dose parenteral glucocorticoids, IVIg, and platelet transfusions 3, 1

Adults with ITP

• Platelet count >50,000: Do not routinely require treatment 3
• Platelet count <20,000 with significant mucous membrane bleeding: Hospitalization is appropriate 3
• Severe, life-threatening bleeding: High-dose parenteral glucocorticoid therapy, IVIg, and platelet transfusions 3

Pregnant Women with ITP

• Platelet count >50,000: No routine treatment required; do not give glucocorticoids or IVIg 3
• Platelet count <10,000 OR 10,000-30,000 in second/third trimester with bleeding: Treatment is required 3
• Third trimester with platelet count <10,000: IVIg is appropriate initial treatment 3
• Maternal platelet count >50,000 is sufficient to prevent complications from excessive bleeding at delivery 3

For Suspected Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis

• Immediately discontinue all potential causative medications if SJS/TEN is suspected with >30% BSA involvement 6
• Initiate IV methylprednisolone 1-2 mg/kg for grade 4 skin toxicity with skin sloughing >30% BSA 6
• Transfer to specialized dermatology unit or burn unit for supportive care 6
• Obtain ophthalmology consultation if mucosal involvement is present 6

For Henoch-Schönlein Purpura

• Cutaneous and joint symptoms only: Oral prednisone 1-2 mg/kg daily for two weeks 4
• Renal involvement with persistent proteinuria: ACE inhibitors or ARBs as first-line therapy 4
• Serial urinalysis and blood pressure monitoring to detect renal involvement early 4

For Pigmented Purpuric Dermatosis

• Narrow-band UVB phototherapy three times weekly until clearance, followed by maintenance therapy 4
• Clinical photography to document extent and response to treatment 4

For Thrombotic Microangiopathy in Lupus Nephritis

• Start plasma exchange and glucocorticoid while awaiting ADAMTS13 activity and antiphospholipid antibody results 3
• Use PLASMIC score to assess probability of thrombotic thrombocytopenic purpura if available 3
• Comanage with experienced hematologist when appropriate expertise is available 3

For Purpura Fulminans

• Protein C replacement therapy if available, particularly if congenital protein C deficiency is suspected 6, 5
• Corticosteroid therapy may successfully repress the inflammatory process if drug-induced vasculitis is identified 7
• Early recognition and accurate identification of underlying cause is essential to reduce mortality and prevent long-term sequelae 5

Critical Pitfalls to Avoid

• Do not transfuse platelets for isolated thrombocytopenia without active bleeding in ITP or vasculitic processes 6
• Do not delay skin biopsy while waiting for laboratory results when vasculitis or drug reaction is suspected 6
• Do not continue potential causative drugs if SJS/TEN is in the differential diagnosis 6
• Do not perform bone marrow aspiration routinely before initiating IVIg therapy for suspected ITP 3
• Do not give prophylactic platelet transfusions to pregnant women with platelet counts >30,000 and no bleeding symptoms 3

Monitoring and Follow-up

• Daily assessment of BSA involvement and progression for spreading purpuric lesions 6
• Brain imaging (ultrasound) should be performed in newborns of mothers with ITP if platelet count at birth is <20,000, or 20,000-50,000 even without neurologic abnormalities 3
• Neonatal platelet count monitoring for 3-4 days after birth in infants of mothers with ITP 3