Correct Answer: B. Hepatitis C
Cryoglobulinemia is a systemic vasculitis characterized by circulating immune complexes that precipitate at temperatures below 37°C. Hepatitis C virus (HCV) is the most common cause of cryoglobulinemia globally and in India, accounting for 50–90% of cases. HCV-associated cryoglobulinemia (typically mixed cryoglobulinemia type II) occurs due to persistent viral antigenemia and formation of immune complexes containing HCV RNA, IgM rheumatoid factor, and IgG. These complexes deposit in small vessels, causing vasculitis affecting skin (palpable purpura), joints (arthralgia), kidneys (membranoproliferative glomerulonephritis), and peripheral nerves (neuropathy). The mechanism involves chronic antigenic stimulation by HCV, leading to B-cell proliferation and monoclonal IgM production. In India, with rising HCV prevalence in certain populations (post-transfusion, PWID), recognizing HCV-associated cryoglobulinemia is clinically important for early diagnosis and antiviral therapy. Serology shows positive HCV antibody/RNA, low C4 complement, and positive rheumatoid factor. Direct-acting antivirals (DAAs) are now the standard of care, often leading to resolution of cryoglobulinemia manifestations.
Why the other options are wrong
A. Diabetes — Diabetes is not associated with cryoglobulinemia. While both are chronic diseases, diabetes causes microvascular complications (retinopathy, nephropathy, neuropathy) through hyperglycemia and glycation, not through immune complex vasculitis. This is an NBE distractor that exploits confusion between different causes of vasculitis and systemic complications. C. Leukaemia — Leukaemia is not a recognized cause of cryoglobulinemia. While hematologic malignancies can cause paraproteinemia and rarely cryoglobulinemia (type I, monoclonal), the classic and most clinically relevant association is with HCV. This option may trap students who conflate cryoglobulinemia with other paraneoplastic syndromes or lymphoproliferative disorders. D. Ovarian cancer — Ovarian cancer has no established association with cryoglobulinemia. This is a pure distractor with no pathophysiologic link. NBE includes this to test whether students can distinguish the well-established HCV–cryoglobulinemia association from unrelated malignancies.
High-Yield Facts
- HCV is the most common cause of mixed cryoglobulinemia type II (80–90% of cases), presenting with palpable purpura, arthralgia, and glomerulonephritis.
- Cryoglobulinemia pathophysiology: immune complexes (HCV antigen + IgM-RF + IgG) precipitate at <37°C, causing small-vessel vasculitis.
- Diagnostic triad for HCV-associated cryoglobulinemia: positive HCV serology/RNA, low C4 complement, positive rheumatoid factor (RF).
- Clinical manifestations: palpable purpura (lower extremities), arthralgia, membranoproliferative GN (hematuria, proteinuria), peripheral neuropathy.
- Treatment: direct-acting antivirals (DAAs) are first-line; rituximab + plasmapheresis for severe vasculitis or renal involvement.
Mnemonics
HCV-CRY mnemonic Hepatitis C → CRYoglobulinemia. HCV is the #1 cause; remember: HCV causes chronic antigenic stimulation → B-cell proliferation → monoclonal IgM-RF → immune complex vasculitis. Cryoglobulinemia Type II features (HCV-associated) Mixed (Type II) = Monoclonal IgM-RF + polyclonal IgG. Purpura, Arthralgia, Glomerulonephritis, Neuropathy = PAGN (remember: HCV-associated cryoglobulinemia causes PAGN).
NBE Trap
NBE pairs cryoglobulinemia with systemic diseases (diabetes, malignancies) to test whether students know the specific viral etiology. The trap is confusing cryoglobulinemia with other causes of vasculitis or systemic complications, rather than recognizing the pathognomonic HCV association.
Clinical Pearl
In Indian clinical practice, a patient presenting with palpable purpura, arthralgia, and hematuria should raise immediate suspicion for HCV-associated cryoglobulinemia, especially in post-transfusion or PWID populations. Check HCV serology, complement levels (C3, C4), and rheumatoid factor—this triad is diagnostic and warrants urgent antiviral therapy to prevent progressive renal disease.
_Reference: Harrison Ch. 356 (Vasculitis); Robbins Ch. 13 (Immunologic Injury); KD Tripathi Ch. 57 (Antivirals)_