Reduced erythrocyte deformability in some hematological diseases: how this can affect the primary hyperviscosity syndromes (PHS) classification

The classification of Roe Wells formulated in 1970 and published on The New England Journal of Medicine distinguishes the primary hyperviscosity syndromes (PHS) in syndrome of polycythemic hyperviscosity, in syndrome of serum hyperviscosity and in syndrome of sclerocythemic hyperviscosity. In polycythemia vera (PV), multiple myeloma (MM), Waldenström’s macroglobulinemia(WM), and monoclonal gammopathy of undetermined significance(MGUS), previously some of us have observed an unexpected behaviour of the erythrocyte deformability. These data have underlined how the hemorheological abnormality present in PV had not been related to the increase of red cell mass only, as well as the hemorheological alteration found in plasmacellular dyscrasias (MM,WM and MGUS) had not been attributable to the increment of plasma viscosity only. The aim of this paper is, therefore, to provide some input for a possible new nosological codification of the primary hyperviscosity syndromes, suggesting some starting points for an accurate reflection, and emphasizing the need of a revision of the Well’s classification used up to now.