Needle‐like cryoglobulin crystals presenting as spurious thrombocytosis

Abstract

A 79-year-old male had anaemia and apparent thrombocytosis on routine blood analysis (haemoglobin 10AE6 g/dl, white blood cell (WBC) count 2AE7 · 10 9 /l, platelet count 916 · 10 9 /l); however, when analysed on an optical analyser, the true platelet count was found to be low (haemoglobin 10AE9 g/dl, WBC count 2AE8 · 10 9 /l, platelet count 79 · 10 9 /l). The apparent thrombocythaemia was due to multiple needle-like crystals that formed as the sample cooled (the upper left panel shows freshly collected blood with early crystal formation, the upper right panel shows prominent needle-like crystals appearing as the blood was allowed to cool). Immunological investigation confirmed a monoclonal immunoglobulin (immunoglobulin Gk 4AE1 g/l) that precipitated on cooling (type 1 cryoglobulin). To confirm the nature of the unusual crystals, they were purified and separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (bottom left panel), and the protein components identified using matrixassisted laser desorption/ionisation-time of flight mass spectrometry and peptide-mass finger printing. The peptidemass fingerprint of one of the protein components (indicated as band B on the gel) is shown in the lower right panel: the three indicated peptides identified this band as being the heavy chain of immunoglobulin. The other major bands (A and C) were identified respectively as albumin (a typical component of cryoglobulin) and immunoglobulin light chain. The cause of the unusual crystal shape seen in this patient may relate to unusual 'self-assembly' characteristics of the monoclonal immunoglobulin.

Thrombocytosis: Diagnostic Evaluation, Thrombotic Risk Stratification, and Risk-Based Management Strategies

“…Spurious thrombocytosis is characterized by the presence of nonplatelet structures in the peripheral blood which are counted as platelets by the automated counters used in modern complete blood counts. A variety of such structures, including needle-like cryoglobulin crystals [ 8 ], cytoplasmic fragments of circulating leukemic cells [ 9 ], bacteria [ 10 ], and red blood cell microvesicles following massive burn injury [ 11 ] are examples of the wide variety of structures that can mimic platelets when analyzed by automated cell counters. Peripheral blood smear evaluation is a simple method to confirm the veracity of a diagnosis of thrombocytosis and should be a part of every evaluation for a cause of thrombocytosis.…”

A Patient with Altered Sensorium and Splenic Abscess Diagnosed to Be a Case of Myeloproliferative Disease: A Case Report

“…Spurious thrombocytosis is characterised by the presence of non-platelet structures in the peripheral blood which are counted as platelets by the automated counters used in modern complete blood counts. A variety of such structures are needle like cryoglobulin crystals [17] , cytoplasmic fragments of circulating leukemic cells [18] , bacteria [19] and red blood cell microvesicles following massive burn injury [20] are examples of structures mimicking platelets.…”

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“…Collections of amorphous or crystalline matter could indicate the existence of cryoglobulin precipitates, which could happen in hepatitis C patients [12].…”