Cytological and ultrastructural assessment of free crystals or precipitates associated with pseudoleukocytosis and pseudothrombocytosis in cryoglobulinemia.
In 3 patients with cryoglobulinemia (case 1: type I: cases 2 and 3: type II) spurious leukocyte and platelet counts were seen using automatic particle counters, with up to 2.5X and 3X counts for leukocytes and platelets respectively, with peculiar volume histograms. All these anomalies were absent with manual counting and were still evident in warmed blood samples from 1 of the 3 patients. The corresponding blood smears showed numerous deposits, rectangular in the type I cryoglobulinemia and flake-like in the other two (type II) patients, responsible for the erroneous automatic counting. Ultrastructural study showed in cases 2 and 3 they consisted of dense amorphous protein clusters; and in case 1, a periodic disposition of hollow rods (each with 21-24 nm external diameter). Comparison with ultrastructure descriptions of isolated cryoglobulins from the literature showed that crystals made of hollow rods might be preferentially associated with monoclonal GK immunoglobulin. Close scrutiny of histograms from automatic cell counters and stained blood films is necessary to detect falsely elevated counts in patients with cryoglobulinemia, and in the management of suppressive therapy.