Figure 4

Relationship between cryoglobulin detection and overt mixed cryoglobulinemia (MC) syndrome. (1) Definite MC syndrome (or cryoglobulinemic vasculitis) is a combination of serological findings (mixed cryoglobulins with RF activity and frequent low C4) and typical clinico-pathological features (purpura, leukocytoclastic vasculitis, and frequent multiple organ involvement); see also Table 3. However, incomplete MC syndrome can be observed at any time during the natural history of the disease; (2) Isolated serological alterations may be detected in the early stages of the disease or during the clinical remission; on the contrary; (3) the absence of serum cryoglobulins in patients with overt MC syndrome may be a transient phenomenon due to the wide variability of the percentage of cryoprecipitable immune-complex during the natural history of the disease or, less frequently, to a switching from 'benign' B-cell lymphoproliferation to malignant lymphoma.