Molecular Testing Specimen Adequacy Summary

• JAK2, CALR, and MPL testing is often performed on peripheral blood specimens in an outpatient setting.
• JAK2 mutations are preferably analyzed in granulocytes.
• Peripheral blood and bone marrow specimens are equally adequate for the identification of JAK2 mutations.
• By extrapolation, CALR and MPL testing on peripheral blood specimens should be equally adequate.

One common scenario for pathologists is determining what testing should be performed on a bone marrow biopsy specimen for a suspected myeloproliferative neoplasm (MPN).  This can be difficult when a clinician has already ordered molecular tests on peripheral blood in the outpatient setting, and a determination need to be made, which tests should be performed (repeated) on a bone marrow sample.

JAK2 mutations are preferably analyzed in granulocytes, which are present in bone peripheral blood and bone marrow sample.  Therefore, such testing on peripheral blood does NOT need to be repeated on the bone marrow sample.  By extrapolation, it is logical that mutation testing for CALR and MPL would have similar accuracy.  Conceivably, if the peripheral blood did not have many granulocytic cells, then testing accuracy may be affected.

References

Larsen TS, Pallisgaard N, Møller MB, Hasselbalch HC. Quantitative assessment of the JAK2 V617F allele burden: equivalent levels in peripheral blood and bone marrow. Leukemia. 2008;22: 194–195. doi:10.1038/sj.leu.2404861

Gong JZ, Cook JR, Greiner TC, Hedvat C, Hill CE, Lim MS, et al. Laboratory practice guidelines for detecting and reporting JAK2 and MPL mutations in myeloproliferative neoplasms: a report of the Association for Molecular Pathology. The Journal of molecular diagnostics : JMD. 2013. pp. 733–744. doi:10.1016/j.jmoldx.2013.07.002