In 1933 Wintrope and Buell described “an extraordinary hyperproteinemia” in a patient suffering from multiple myeloma. She “presented symptoms of coldness, blanching and a peculiar mottling of the extremities, as well as other signs of disturbed circulation, and was found to have, in her blood, a voluminous quantity of a substance which invariably was precipitated immediately on withdrawal of the blood from the body”.1

Since then several authors have analysed the cryoprecipitation reaction as well as the cryoprecipitated proteins.2 ,3 In 1974, Brouet and colleagues proposed a classification based on the type of protein that constitutes the cryoprecipitate.4 This classification has always had the disadvantage of associating diseases with very different aetiology and outcome, in the same group. In addition to cryoglobulinaemia secondary to well defined pathologies, Brouet and colleagues realised that a large proportion (30%) of patients had no known disease. This group of idiopathic cryoglobulinaemia has been referred to as “essential” cryoglobulinaemia. Since our initial report in 1990,5 it has become clear that most of these essential cryoglobulinaemias are in fact associated with hepatitis C virus infection. The description of a cryoglobulinaemia therefore has to take into account this important new finding.