Which of these is not an indication for plasma exchange: Henoch-Schonlein purpura (HSP), Systemic Lupus Erythematosus (SLE), small vessel vasculitis, or Myasthenia Gravis (MG)?

Henoch-Schönlein Purpura is Not an Indication for Plasma Exchange

Henoch-Schönlein purpura (HSP) is not an indication for plasma exchange therapy, unlike the other conditions listed in the question. While plasma exchange is recognized as a therapeutic option for certain autoimmune and inflammatory conditions, current guidelines and evidence do not support its routine use in HSP.

Evidence-Based Indications for Plasma Exchange

Myasthenia Gravis

Plasma exchange is an established treatment for myasthenia gravis, particularly in crisis situations or before surgery. According to neurological guidelines, plasma exchange is recommended alongside IVIG as first-line immunotherapy for myasthenia gravis when rapid improvement is needed 1.

Small Vessel Vasculitis

Plasma exchange has a role in ANCA-associated small vessel vasculitis. The EULAR guidelines specifically state: "Plasma exchange may be considered as part of therapy to induce remission in GPA or MPA for those with a serum creatinine >300 µmol/L due to active glomerulonephritis" 2. This recommendation is based on high-quality evidence (level 1a).

Systemic Lupus Erythematosus (SLE)

For SLE with certain complications, plasma exchange may be indicated:

• In catastrophic antiphospholipid syndrome associated with SLE, plasma exchange is often used and "has been associated with improved patient survival in retrospective studies" 2
• For thrombotic thrombocytopenic purpura (TTP) associated with SLE, guidelines recommend plasma exchange as part of treatment 2

Why HSP Does Not Warrant Plasma Exchange

Henoch-Schönlein purpura (IgA vasculitis) is primarily managed with supportive care because:

1. It is typically self-limiting, with spontaneous resolution in 94% of children and 89% of adults 3, 4

2. First-line treatment for HSP with renal involvement typically involves corticosteroids, not plasma exchange 3

3. Current guidelines do not include plasma exchange as a standard treatment for HSP

4. While there are isolated case reports of plasma exchange being used in severe adult HSP 5, these represent exceptional cases rather than standard practice

Treatment Algorithm for HSP

1. Mild disease (typical presentation):

   • Supportive care only
   • Pain management for joint symptoms
   • Monitor for complications

2. Moderate disease with significant symptoms:

   • Oral prednisone (1-2 mg/kg daily for two weeks) for abdominal and joint symptoms 3
   • Regular monitoring of renal function

3. Severe disease with renal involvement:

   • High-dose steroids plus immunosuppressants (e.g., cyclophosphamide, mycophenolate) 4
   • NOT plasma exchange as first-line therapy

Pitfalls to Avoid

1. Don't confuse HSP with other vasculitides: While plasma exchange is indicated for certain small vessel vasculitides (ANCA-associated), HSP has a different pathophysiology involving IgA immune complex deposition.

2. Don't underestimate HSP in adults: Adult HSP can be more severe than pediatric cases, with higher risk of renal complications, but even then, standard therapy does not include plasma exchange.

3. Don't miss overlapping conditions: Rarely, patients may present with features of HSP but later develop other autoimmune conditions like SLE 6 that might warrant different treatment approaches.

In conclusion, while plasma exchange has established roles in treating myasthenia gravis, certain small vessel vasculitides, and specific complications of SLE, it is not a standard indication for Henoch-Schönlein purpura.