18F-FLT (PET/CT) in Prefibrotic/Early Primary Myelofibrosis and Essential Thrombocythemia

Inclusion Criteria: Age 18 year old or above Patient accept to sign inform consent ECOG (Eastern CooperativeOncology Group) performance less than or equal 2

• Cases fulfilling WHO (World Health Organization) 2016 diagnostic criteria for PMF: WHO criteria for prefibrotic/early primary myelofibrosis (prePMF) Major criteria:

1. Megakaryocytic proliferation and atypia, without reticulin fibrosis > grade 1*,accompanied by increased age-adjusted BM cellularity, granulocytic proliferation andoften decreased erythropoiesis

2. Not meeting the WHO criteria for BCR-ABL1+ ((BCR-ABL = fusion gene from BCR (breakpoint cluster region gene/BCR gene product) and ABL (Abelson proto-oncogene))CML (chronic myelogenous leukemia), PV (Polycythemia Vera), ET, myelodysplasticsyndromes, or other myeloid neoplasms

3. Presence of JAK2, CALR or MPL mutation or in the absence of these mutations, presenceof another clonal marker**or absence of minor reactive BM reticulin fibrosis. Minor criteria: Presence of at least one of the following, confirmed in two consecutive determinations:

4. Anemia not attributed to a comorbid condition

5. Leukocytosis >11 x 109/L

6. Palpable splenomegaly

7. LDH (Lactate dehydrogenase) increased to above upper normal limit of institutionalreference range. Diagnosis of prePMF requires meeting all three major criteria, and at least one minorcriterion **in the absence of any of the 3 major clonal mutations, the search for the mostfrequent accompanying gene mutations (e.g. ASXL1, EZH2, TET2, IDH1/IDH2, SRSF2, SF3B1) areof help in determining the clonal nature of the disease.

*** minor (grade 1) reticulin fibrosis secondary to infection, autoimmune disorder or otherchronic inflammatory conditions, hairy cell leukemia or other lymphoid neoplasm, metastaticmalignancy, or toxic (chronic) myelopathies WHO diagnostic criteria essential thrombocythemia Major criteria Platelet count ≥450 × 109/L Bone marrow biopsy showing proliferation mainly of the megakaryocyte lineage withincreased numbers of enlarged, mature megakaryocytes with hyperlobulated nuclei. Nosignificant increase or left shift in neutrophil granulopoiesis or erythropoiesis and veryrarely minor (grade 1) increase in reticulin fibers. Not meeting WHO criteria for BCR-ABL1+ CML, PV, PMF, myelodysplastic syndromes, or othermyeloid neoplasms Presence of JAK2, CALR, or MPL mutation Minor criterion Presence of aclonal marker or absence of evidence for reactive thrombocytosis Diagnosis of ET requiresmeeting all 4 major criteria or the first 3 major criteria and the minor criterion

Exclusion Criteria:

• Patient not fulfilling the inclusion criteria.

• Vulnerable groups: pregnant, minors, prisoners will not be included.

• Bone marrow will be collected as part of the routine diagnostic work-up. No extra bonemarrow material will be collected solely for the aim of the study.