Proposed diagnostic criteria and classification of basophilic leukemias and related disorders

Abstract

Basophils form a distinct cell lineage within the hematopoietic cell family. In various myeloid neoplasms, including chronic myeloid leukemia, basophilia is frequently seen. Acute and chronic basophilic leukemias, albeit rare, have also been described. However, no generally accepted criteria and classification of basophilic leukemias have been presented to date. To address this unmet need, a series of Working Conferences and other meetings were organized between March 2015 and March 2016. The current article provides a summary of consensus statements from these meetings, together with proposed criteria to delineate acute basophilic leukemia (ABL) from chronic basophilic leukemia (CBL) and primary forms of the disease where no preceding myeloid malignancy is detected, from the more common 'secondary' variants. Moreover, the term hyperbasophilia (HB) is proposed for cases with a persistent peripheral basophil count ⩾1000 per μl of blood. This condition, HB, is highly indicative of the presence of an underlying myeloid neoplasm. Therefore, HB is an important checkpoint in the diagnostic algorithm and requires a detailed hematologic investigation. In these patients, an underlying myeloid malignancy is often found and is then labeled with the appendix -baso, whereas primary cases of ABL or CBL are very rare. The criteria and classification proposed in this article should facilitate the diagnosis and management of patients with unexplained basophilia and basophil neoplasms in routine practice, and in clinical studies.

The underestimated role of basophils in Ph+ chronic myeloid leukaemia

“…In patients with CML, an increased production of basophils and of basophil‐committed CFU is a typical finding 12, 27. In almost all cases, the criteria for hyperbasophilia (HB: >1000 basophils per microlitre blood14) are fulfilled. In accelerated phase CML, massive basophilia (>20% basophils) is often found.…”

“…CML basophils also display CD203c (Figure 1). Overall, CD203c is a robust and valuable parameter to quantify the total (immature plus mature) basophil compartment in the PB and BM in healthy individuals and in patients with CML 14. However, although basophilia is of major prognostic impact in these patients, CD203c has not yet been tested as a prognostic marker in CML.…”

“…By contrast, in AP and BP, additional factors and pro‐oncogenic molecules play a critical role in disease progression and drug resistance 4, 5, 6, 9, 10, 11. A key laboratory feature of patients with advanced CML is marked and sometimes even excessive basophilia 12, 13, 14. In addition, a number of previous and more recent data suggest that marked basophilia is a significant prognostic variable in CML at diagnosis 15, 16, 17, 18…”

FLT-3 ITD Positive Acute Basophilic Leukemia with Rare Complex Karyotype Presenting with Acute Respiratory Failure: Case Report

“…Acute basophilic leukemia management remains poorly defined, relying on cytarabine and anthracycline-based induction regimens, palliative cytoreductive treatment, targeted therapies (tyrosine kinase inhibitors) or allogeneic stem cell transplant in selected cases [7,14]. Shortened disease free survival (DFS) or refractory disease are common among acute basophilic leukemia patients [7,14].…”

“…Noteworthy, even though multiple chromosomal abnormalities have been reported involving chromosomes 1, 2,6,7,8,11,12,16,17,19,21 and X, no recurrent cytogenetic or molecular anomalies have been described in acute basophilic leukemia patients [3,[5][6][7][8][9][10][11][12][13]. Acute basophilic leukemia management remains poorly defined, relying on cytarabine and anthracycline-based induction regimens, palliative cytoreductive treatment, targeted therapies (tyrosine kinase inhibitors) or allogeneic stem cell transplant in selected cases [7,14]. Shortened disease free survival (DFS) or refractory disease are common among acute basophilic leukemia patients [7,14].…”