Table 4.

Proposed criteria for the classification of patients with mixed cryoglobulinaemia

Criteria	Major	Minor
Serological	Mixed cryoglobulins	Rheumatoid factor+
	Low C4	HCV+
		HBV+
Pathological	Leucocytoclastic vasculitis	Clonal B cell infiltrates (liver and/or bone marrow)
Clinical	Purpura	Chronic hepatitis
		Membranoproliferative glomerulonephritis
		Peripheral neuropathy
		Skin ulcers

HCV+ or HBV+: markers of hepatitis C virus or hepatitis B virus infection (anti-HCV ±HCV RNA; HBV DNA or HBV surface antigen).

“Definite” mixed cryoglobulinaemia syndrome:

(a) Serum mixed cryoglobulins (±low C4) + purpura + leucocytoclastic vasculitis.

(b) Serum mixed cryoglobulins (±low C4) + 2 minor clinical symptoms + 2 minor serological/pathological findings.

“Incomplete” or “possible” mixed cryoglobulinaemia syndrome:

(a) Mixed cryoglobulins or low C4 + 1 minor clinical symptom + 1 minor serological ±pathological findings.

(b) Purpura and/or leucocytoclastic vasculitis + 1 minor clinical symptom + 1 minor serological ±pathological findings.

(c) Two minor clinical symptoms + 2 minor serological ± pathological findings.

“Essential” or “secondary” mixed cryoglobulinaemia:

Absence or presence of well known disorders (infectious, immunological, or neoplastic) at the time of the diagnosis.