Type I Cryoglobulinaemia — SCE Rheumatology MCQ

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HardVasculitisType I CryoglobulinaemiaSCE Rheumatology

A 50-year-old man presents with recurrent cold-induced painful purpura, acral cyanosis and a digital ulcer. Skin biopsy shows non-inflammatory hyaline thrombi occluding small dermal vessels. Immunofixation of the cryoprecipitate identifies monoclonal IgM kappa without a polyclonal IgG component, and serum immunofixation shows the same paraprotein. Which underlying diagnosis should be investigated as a priority?

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Correct answer: B — Waldenström macroglobulinaemia

The monoclonal IgM-kappa cryoprotein without polyclonal IgG defines type I cryoglobulinaemia. This is a manifestation of an underlying clonal B-cell or plasma-cell disorder; with an IgM paraprotein, Waldenström macroglobulinaemia/lymphoplasmacytic lymphoma is the leading diagnosis. In a UK-led cohort of monoclonal IgM type I cryoglobulinaemia, 76% of patients had Waldenström macroglobulinaemia, with smaller proportions having another lymphoma or IgM MGUS. Cold-induced acral ischaemia and non-inflammatory hyaline vascular thrombosis also favour type I disease. Hepatitis C is principally associated with type II mixed cryoglobulinaemia, which contains monoclonal rheumatoid-factor IgM complexed with polyclonal IgG. Sjögren syndrome, SLE and rheumatoid arthritis are likewise more characteristic causes of mixed, rather than isolated monoclonal, cryoglobulinaemia.

Reference: Khwaja J et al. Clinical and clonal characteristics of monoclonal immunoglobulin M-associated type I cryoglobulinaemia. British Journal of Haematology. 2024;204(1):177-185. https://pubmed.ncbi.nlm.nih.gov/37726004/