Introduction JAK2 1 5 FIP1L1–PDGFRA 6 7 BCR–ABL BCR/ABL 8 8 9 It is well known that PV has a median survival of 10 years, ET of 10–15 years, but CIMF of only 4 years. However, the clinical course in CMPD ranges from a few months with rapid leukemic transformation to several decades. These uncertainties in prognosis and the similarities in the clinical and morphological phenotypes at diagnosis plead for inclusion of other than clinical and morphologic parameters only into classification. BCR/ABL JAK2 1 5 10 BCR/ABL 11 6 7 12 BCR/ABL Preanalytic conditions To achieve optimal conditions in the diagnostic procedures, a standardized preparation of the samples and optimal conditions for transport are essential in the CMPD: Cytomorphology requires 3 ml bone marrow and 2 ml peripheral blood anticoagulated with ethylenediaminetetraacetic acid (EDTA), being aware that cytomorphology is hampered by heparine. Cytogenetics, in contrast, requires 5–10 ml heparinized bone marrow and 10–20 ml heparinized peripheral blood, as cultivation of metaphases is nearly inhibited by EDTA which induces apoptosis of cells. Multiparameter flow cytometry and all molecular genetic methods can be performed either on EDTA or heparinized material. Trephine biopsies should be performed for histomorphology and immunohistochemistry and allow cytomorphological evaluation by smears from the trephine cylinder in case of a dry tap. In the latter case, also for cytogenetics, a trephine cylinder can be transferred to isotone saline solution plus heparine, which, in many cases, makes metaphases after cultivation in cytogenetic medium possible. Cytomorphology in CMPD FIP1L1–PDGFRA 9 9 10 13 8 8 9 9 10 14 9 15 17 Histomorphology in CMPD Bone marrow histology has a central role in the diagnosis of CMPD. Staining is performed according to Giemsa, PAS, and chloroacetate esterase. Gomori silver impregnation allows assessment of reticulin fibers to quantify bone marrow connective tissue. 8 18 19 19 20 10 18 10 21 BCR/ABL BCR/ABL 9 22 25 22 ABL PDGFRA PDGFRB 9 23 26 Interphase (IP-), metaphase (HMF-), and 24-color fluorescence in situ hybridization (FISH) may further confirm and clarify the results of the chromosome banding analyses. IP-FISH probes can be used for future MRD studies. Nearly all typically observed aberrations—e.g., +8, +9, gain of 9p, or del(20q)—can be monitored. 27 30 9 22 31 23 26 9 25 23 31 1 Table 1 8 9 22 23 52 69   Karyotype abnormalities Molecular markers Molecular MRD markers CML BCR–ABL BCR/ABL + PV In some cases: +8, +9, del(20q), del(13q), del(1p) JAK2 + JAK2 CIMF In some cases: del(13q), del(20q), +8, +9, partial trisomy 1q JAK2 + MPL ET In rare cases +8, +9, del(13q),  JAK2 + MPL CMPD-U In some cases +8, +9, del(20q) JAK2 + In rare cases 8p11 translocations FGFR1 CEL/HES in some cases: +8, i(17q), PDGFRA/FIP1L1 + CNL in some cases: +8, +9, del(20q) − − CMML −7, +8, del(20q) NRAS + ETV6-PDGFRB FGFR1-ZNF198 ABL ETV6-ABL 32 FGFR1-ZNF198 FGFR1 12 PDFRB ABL 32 BCR/ABL BCR/ABL JAK2 1 5 JAK2 3 5 JAK2 33 JAK2 10 JAK2 26 34 JAK2 35 11 JAK2 JAK2 BCR/ABL JAK2 1 36 37 17 38 JAK2 39 40 JAK2 JAK2 JAK2 40 41 MPL 42 44 Chronic neutrophilic leukemia 9 8 8 45 46 JAK2 4 22 37 45 48 BCR–ABL BCR 49 50 Hypereosinophilic syndrome/chronic eosinophilic leukemia 6 7 51 53 9 8 54 FIP1L1–PDGFRA CHIC2 FIP1L1 PDGFRA FIP1L1–PDGFRA 55 56 PDGFRA PDGFRB FGFR1 JAK2 9 57 PDGFRA PDGFRB 6 7 53 58 32 59 60 Chronic myelomonocytic leukemia 8 9 9 22 61 NRAS 61 63 JAK2 1 4 37 Remission criteria in the CMPD 64 64 Approach to a diagnostic algorithm in the CMPD 1 BCR/ABL Fig. 1 BCR/ABL HES CEL PV CIMF CMPD-U ET RARS-T CMML MFC RT-PCR Dashed line  22 JAK2 65 NRAS PDGF The chromosomal aberrations as revealed by chromosome banding analyses—e.g., +8, +9, del(20q)—can be verified by FISH techniques. This further allows the selection of IP probes for distinct numerical and structural aberrations to provide parameters for MRD diagnostics. JAK2 66 JAK2 JAK2 JAK2 JAK2 10 BCR–ABL BCR–ABL JAK2 67 FIP1L1–PDGFRA Conclusions BCR/ABL 8 FGFR1 PDGFRA PDGFRA ABL JAK2 JAK2 13 PRV1 JAK2 3 2 34 JAK2 40 41 MPL 42 44 JAK2 10 68 JAK2 10 FIP1L1–PDGFRA 6 52 BCR/ABL 32 JAK2 11 BCR/ABL 64 BCR/ABL