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Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Waldenstrom macroglobulinaemia

Haematology and transfusion · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Symptomatic IgM hyperviscosity

Visual disturbance, mucosal bleeding, headache, confusion, seizure, dyspnoea or heart failure with high IgM requires clinical action before systemic therapy can lower production.

Action: Use ABCDE assessment, obtain fundal examination, FBC, renal, coagulation, IgM and serum viscosity without delaying treatment, avoid non-essential red-cell transfusion and perform urgent therapeutic plasma exchange of about 1–1.5 plasma volumes followed promptly by clone-directed therapy.

Synopsis

Confirm marrow lymphoplasmacytic lymphoma with an IgM paraprotein, recognise IgM-mediated emergencies and choose symptom-led therapy that avoids hyperviscosity, rituximab-flare and bleeding harm.

  • WM requires an IgM monoclonal gammopathy plus marrow infiltration by lymphoplasmacytic lymphoma; serum IgM concentration alone does not establish the diagnosis.
  • First-line confirmation is marrow aspirate and trephine with morphology, flow and MYD88 L265P testing; assess CXCR4 when it changes BTK-inhibitor expectations.
  • Do not treat an asymptomatic IgM number: indications include symptomatic anaemia or cytopenia, hyperviscosity, bulky disease, B symptoms and clinically important IgM-mediated organ injury.
  • Clinical hyperviscosity is an emergency even if a numerical viscosity threshold is not reached; examine the fundi and arrange urgent plasma exchange.
  • Plasma exchange removes IgM quickly but is temporary; follow with clone-directed therapy or the paraprotein rebounds.
  • Avoid non-essential red-cell transfusion before viscosity is reduced because increased cellular volume can worsen microcirculatory flow.
  • Rituximab can cause an IgM flare, so reduce IgM with plasma exchange or non-rituximab cytoreduction and defer rituximab in high-risk hyperviscosity contexts.
  • First-line options include bendamustine–rituximab, dexamethasone–rituximab–cyclophosphamide and BTK inhibition selected from pace, genetics, neuropathy, cardiac and bleeding risk.
  • Zanubrutinib is given 320 mg daily or 160 mg twice daily and requires bleeding, infection, blood-pressure, rhythm and CYP3A review.
  • Repeat tissue or PET-directed biopsy for sudden focal growth or LDH rise because transformed lymphoma needs an aggressive pathway.

Key red flags

Retinal haemorrhage or venous engorgement, mucosal bleeding, confusion, ataxia, seizure or heart failure is symptomatic hyperviscosity and requires urgent plasma exchange.

Cold-induced acrocyanosis, haemolysis, purpura, renal injury or neuropathy can be IgM-mediated despite modest tumour bulk and may itself indicate treatment.

Rapid node growth, disproportionate LDH, severe B symptoms or extranodal mass raises histological transformation and requires urgent PET-directed biopsy.

Rituximab can transiently raise IgM; giving it alone to a patient with very high IgM or hyperviscosity can precipitate deterioration.

Hyperviscosity

Visual blur, retinal haemorrhage, mucosal bleeding, headache, vertigo, confusion or dyspnoea requires urgent exchange assessment.

Investigation priorities

01
Reference standard: marrow aspirate and trephineFirst stepReference standard

Demonstrate lymphoplasmacytic lymphoma and distinguish plasma-cell and marginal-zone alternatives.

Management branches

IgM monoclonal proteinSeparate precursor, lymphoma and myeloma

SPEP or immunofixation detects monoclonal IgM.

  1. Assess hyperviscosity, neuropathy, haemolysis, cryoglobulin, renal, nodes, spleen, cytopenia and constitutional symptoms.
  2. Perform marrow morphology, flow and MYD88 with CT and selected t(11;14) or plasma-cell studies.
  3. Classify IgM MGUS, WM, marginal-zone lymphoma, IgM myeloma or an IgM-related disorder and set observation or treatment.

Key medicines

Therapeutic plasma exchangeExchange approximately 1–1.5 calculated plasma volumes urgently with albumin-based replacement under the apheresis protocol, repeating according to clinical response, fundal findings, IgM and viscosity rebound.It is temporary and must be followed by clone-directed therapy. Monitor access, haemodynamics, calcium, coagulation and IgM rebound; avoid unnecessary red-cell transfusion before viscosity is reduced.
Bendamustine with rituximabGive bendamustine 90 mg/m² IV on days 1 and 2 with rituximab 375 mg/m² IV day 1 every 28 days for up to six cycles, modifying through the WM protocol and sequencing rituximab when flare risk is high.Screen hepatitis B, provide prophylaxis where indicated and monitor infusion reaction, IgM flare, prolonged CD4 lymphopenia, infection, cytopenia, renal and skin toxicity. Use Pneumocystis and antiviral prevention according to protocol and avoid pregnancy.
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Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • British Society for Haematology Waldenstrom guidelineUK diagnosis, hyperviscosity, treatment indications and regimen guidance.
  • British Society for Haematology apheresis guidelineUK plasma-exchange practice for symptomatic hyperviscosity.
  • Brukinsa Summary of Product CharacteristicsExact zanubrutinib dose, CYP3A, bleeding and reproductive safety.
  • MabThera Summary of Product CharacteristicsRituximab administration, viral reactivation and infusion safety.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom