In a postoperative patient who develops new purpura, livedo, digital ischemia, neuropathy, fever, or organ dysfunction suggestive of vasculitis, what is the immediate evaluation and management?

Postoperative Vasculitis: Immediate Evaluation and Management

In a postoperative patient developing signs suggestive of vasculitis (purpura, livedo, digital ischemia, neuropathy, fever, organ dysfunction), immediately obtain ANCA testing (immunofluorescence plus MPO/PR3 ELISA), complete blood count, ESR/CRP, comprehensive metabolic panel, urinalysis with microscopy, and a deep skin biopsy extending to subcutis from the most inflamed lesion—while simultaneously considering drug-induced vasculitis and infection as the most common postoperative mimics. 1, 2, 3

Critical First Steps: Rule Out Infection and Drug Reactions

Postoperative "vasculitis" is infection or drug reaction until proven otherwise:

• Examine the surgical wound directly by removing dressings—group A streptococcal and clostridial infections can present 1-3 days postoperatively with systemic signs mimicking vasculitis 1
• Review all medications started perioperatively—drug-induced vasculitis is the most common form of vasculitis, and withdrawal of the offending agent alone often induces prompt resolution without need for immunosuppression 3
• Culture blood, urine, and any suspicious skin lesions—postoperative fever beyond 96 hours is likely infectious, and systemic infection (especially Staphylococcus aureus) can trigger immune-mediated vasculitic reactions 1, 4

Immediate Diagnostic Workup

Laboratory evaluation must include:

• ANCA testing with both immunofluorescence and antigen-specific assays (MPO and PR3)—essential for diagnosing ANCA-associated vasculitis, which presents with rapidly progressive glomerulonephritis, pulmonary-renal syndrome, or multi-organ involvement 1, 2
• ESR and CRP—markedly elevated inflammatory markers (ESR >100 mm/h, CRP >100 mg/L) support active vasculitis, though normal values do not exclude it 1, 5
• Urinalysis with microscopy—look for red blood cell casts, proteinuria, or hematuria indicating glomerulonephritis 1, 2
• Complete blood count—thrombocytosis >400 × 10³/μL supports large vessel vasculitis; anemia and leukocytosis are nonspecific 5

Tissue diagnosis is mandatory:

• Obtain deep skin biopsy extending to subcutis from the most tender, erythematous, or purpuric lesion—diagnostic yield exceeds 70% when the appropriate site is selected 1, 2
• Request serial sections and direct immunofluorescence—distinguishes IgA-associated vasculitis (Henoch-Schönlein purpura) from IgG/IgM-associated vasculitis, and identifies immune complex deposition 6, 7
• Coexistence of pan-dermal small-vessel vasculitis and subcutaneous muscular-vessel vasculitis indicates connective tissue disease, ANCA-associated vasculitis, or malignancy-associated vasculitis 6

Structured Clinical Assessment

Perform systematic organ-specific evaluation:

• Skin: Document distribution of purpura, livedo racemosa, nodules, ulcers, or digital gangrene—palpable purpura indicates dermal superficial small-vessel vasculitis, while nodular erythema and deep ulcers implicate deep dermal or subcutaneous muscular-vessel vasculitis 6, 7
• Neurologic: Test for mononeuritis multiplex (asymmetric peripheral neuropathy affecting multiple nerves)—characteristic of medium-vessel vasculitis 2
• Renal: Check creatinine and urinalysis—rapidly progressive glomerulonephritis is a medical emergency requiring immediate treatment 2
• Pulmonary: Assess for hemoptysis, dyspnea, or infiltrates on chest imaging—pulmonary-renal syndrome requires emergent immunosuppression 2
• Vascular: Obtain four-extremity blood pressures and palpate all peripheral pulses—>10 mmHg discrepancy between arms or absent pulses suggests large vessel vasculitis 8

Immediate Management Decisions

If true vasculitis is confirmed and infection excluded:

• For small-medium vessel vasculitis with organ-threatening disease (rapidly progressive glomerulonephritis, pulmonary hemorrhage, severe neuropathy): initiate high-dose glucocorticoids (1 mg/kg/day prednisone, maximum 60-80 mg/day) plus rituximab 375 mg/m² IV weekly × 4 weeks or cyclophosphamide (2 mg/kg/day oral or IV pulses) 2
• For large vessel vasculitis (limb claudication, vascular bruits, blood pressure discrepancies): start high-dose oral prednisone 40-60 mg/day immediately, even before diagnostic confirmation, and obtain CT or MR angiography of the aorta and major branches 8, 5
• For mild cutaneous-limited vasculitis: leg elevation, avoidance of prolonged standing, and NSAIDs may suffice; colchicine or dapsone are first-line agents for recurrent disease 6

Critical Supportive Measures During Immunosuppression

Mandatory prophylaxis includes:

• Pneumocystis jiroveci prophylaxis with trimethoprim-sulfamethoxazole during cyclophosphamide or high-dose glucocorticoid therapy 2
• Osteoporosis prophylaxis with calcium, vitamin D, and bisphosphonates for patients receiving prolonged glucocorticoids 2
• Mesna for bladder protection when using cyclophosphamide to prevent hemorrhagic cystitis 2

Common Pitfalls to Avoid

Do not mistake infection for vasculitis:

• Postoperative spinal infection with Staphylococcus aureus has presented as systemic vasculitis with diffuse erythema and nephritis, resolving only after surgical debridement and antibiotics 4
• Metal allergy (nickel in titanium alloy implants) can trigger vasculitis-like reactions postoperatively, requiring corticosteroids but ultimately resolving after implant revision 4

Do not delay treatment for biopsy results:

• If clinical suspicion for life-threatening vasculitis is high (pulmonary-renal syndrome, rapidly progressive glomerulonephritis), start high-dose glucocorticoids immediately while awaiting biopsy confirmation 5, 2
• Temporal artery biopsy for suspected giant cell arteritis can be obtained up to 2 weeks after starting glucocorticoids without compromising diagnostic yield 5

Do not assume elevated inflammatory markers alone indicate active vasculitis:

• Isolated elevation of ESR/CRP without clinical symptoms does not warrant escalation of immunosuppression—observation and more frequent monitoring are appropriate 1, 5
• In Takayasu arteritis, ESR and CRP are normal in 50% of patients with active disease—disease activity requires clinical symptoms, vascular examination findings, and imaging evidence of new or progressive vascular lesions 8