Spotlight on anagrelide hydrochloride for the treatment of essential thrombocythemia

Figures & data

Table 1 Comparison of the revised 2016 WHO¹ and proposed 2014 BCSH diagnostic criteria² for ET

WHO diagnostic criteria for ET	BCSH diagnostic criteria for ET
	Diagnosis requires AI-A3 or AI+A3-A5
Major criteria
Platelet count >450x 10^9/L	A1	Sustained platelet count >450x10^9/L
BM biopsy showing proliferation mainly of the megakaryocyte lineage with increased numbers of enlarged, mature megakaryocytes with hyperlobulated nuclei. No significant increase or left shift in neutrophil granulopoiesis or erythropoiesis and very rarely minor (grade 1) increase in reticulin fibers	A2	Presence of an acquired pathogenetic mutation (eg. in the JAK2, CALR or MPL genes)
Not meeting the wHO criteria for BCR-ABLi CML, Pv, PMF, MDSs or other myeloid neoplasms	A3	No other myeloid malignancy, especially Pv, PMF, CML or MDS
Presence of JAK2, CALR or MPL mutation	A4	No reactive cause for thrombocytosis and normal iron stores
Minor criterion
Presence of a clonal marker or absence of evidence for reactive thrombocytosis	A5	BM aspirate and trephine biopsy showing increased megakaryocyte numbers displaying a spectrum of morphology with predominant large megakaryocytes with hyperlobulated nuclei and abundant cytoplasm. Reticulin is generally not increased (grades 0-2/4 or grade 0/3)
Diagnosis of ET requires meeting all four major criteria or the first three major criteria and the minor criterion		PV: excluded by a normal hematocrit in an iron-replete patient PMF: indicated by presence of significant BM fibrosis (greater than or equal to grade 2/3 or 3/4 reticulin) and palpable splenomegaly, blood film abnormalities (circulating progenitors and tear-drop cells) or unexplained anemia CML: excluded by absence of BCR-ABLI fusion from BM or peripheral blood MDS: excluded by absence of dysplasia on examination of blood film and BM aspirate

Note: Data from Arber et al¹ and Harrison et al.²

Abbreviations: WHO, World Health Organization; BCSH, British Committee for Standards in Haematology; ET, essential thrombocythemia; BM, bone marrow; CML, chronic myeloid leukemia; PV, polycythemia vera; PMF, primary myelofibrosis; MDS, myelodysplastic syndrome.