Enzyme negative blastic transformation of chronic myeloproliferative disorders: immunophenotyping of the blastic cell population.

Enzyme negative blast cells from 27 patients with chronic myeloproliferative disorders (CMPDs) in blastic transformation were analysed with a panel of monoclonal antibodies (MoAbs). According to morphologic features of the bone marrow and laboratory data, the 27 cases were divided into 8 cases of myelofibrosis (MF), 3 cases of chronic megakaryocytic granulocytic myelosis (CMGM) and 16 cases of chronic myeloid leukaemia (CML). Of the 27 cases, 23 showed a positive reaction with myeloid MoAbs, but in 12 cases expressing myeloid markers, megakaryocytic, monocytic or lymphoid cell features were also detected. In 7 cases of MF, 1 case of CMGM and 1 case of CML a bilineage, myelo-megakaryocytoid immunophenotype of peripheral blast cells was seen. Of the 4 patients with CML expressing lymphoid markers, 2 showed early B-cell, 1 T-cell surface antigens, and 1 both myeloid and early B-cell features. In this group of cytochemically immature blastic transformation of CMPD, only 1 case was termed "undifferentiated" blastic transformation.     

Nucleolar organizer regions of megakaryocytes in chronic myeloproliferative disorders

Summary To study megakaryocyte activation, the argyrophilic staining method of nucleolar organizer regions (AgNOR) has been applied to decalcified bone marrow biopsies of 16 individuals with no haematopoietic disorders and 59 patients with chronic myeloproliferative disease. Of the 59 patients, 18 had chronic myeloid leukaemia (CML), 21 chronic megakaryocytic granulocytic myelosis (CMGM), 13 polycythaemia vera (PV) and 7 essential thrombocythaemia (ET). The AgNOR number of megakaryocytes in CML was significantly lower, and in CMGM, PV and ET significantly higher than in healthy individuals. The high number and the clusters of fine-grained AgNORs of megakaryocytes in CMGM, PV and ET are suggestive of active, proliferating cells. The AgNOR number of megakaryocytes and the platelet counts of the patients did not show a convincing correlation. In CMGM, PV and ET the pyknotic, heterochromatinized megakaryocytes with narrow rims of cytoplasm called bare (nude) nuclei, possessed few, large AgNOR granules. The AgNOR staining of bare nuclei and the roughly identical number of granules found in CMGM, PV and ET indicate a common, active mechanism of apoptosis.     

Osteoclasts and bone remodeling in chronic myeloproliferative disorders. A histochemical and morphometric study on trephine biopsies in 165 patients

In 165 patients with chronic myeloproliferative disorders (CMPD) a morphometric and histochemical study was performed on trephine biopsies of the bone marrow to elucidate osseous remodeling by assessment of trabecular bone area (planimetry) and number of osteoclasts. Osteoclastic elements were identified by the tartrate-resistant acid phosphatase method. In addition to control specimens (n = 20) subtypes of CMPD included chronic myeloid leukemia (CML, n = 65), primary (essential) thrombocythemia (PTH, n = 25), polycythemia vera rubra (P. vera, n = 25) and agnogenic myeloid metaplasia (AMM, n = 50). AMM was discriminated into a so-called early hyperplastic stage without gross myelofibrosis (n = 19) and an overt or advanced stage showing fibro-osteosclerotic changes (n = 31). Total area of trabecular bone and counts for osteoclasts (uni- and multi-nucleated cells as well as a-nuclear cytoplasmic fragments) were not significantly increased in CML, PTH, P. vera and in the initial hypercellular stages of AMM. In contrast to these results, in advanced stages of AMM there was a significant increase in total bone area associated with a high count for all osteoclastic elements and apparently also an increased number of osteoblasts. It is speculated that the marked increase in osteoclastic-osteoblastic elements in late stages of AMM possibly reflects an imbalance of calcitriol (1.25-dihydroxyvitamin D 3) on skeletal homeostasis. This abnormal osseous remodeling may be mediated by the atypical megakaryocytic proliferation in this disorder, which is always a conspicuous feature of bone marrow biopsies.     

Chronic megakaryocytic granulocytic myelosis — CMGM

Summary In 1,083 core biopsies of the bone marrow with myeloproliferative diseases 454 cases or 42% were found to have neoplastic megakaryopoiesis. Neoplasia of megakaryocytes was assumed from the conspicuous cytological atypicality revealed by light microscopy, extending and confirming earlier ultrastructural findings. Histopathology of the bone marrow in these patients was described as chronic megakaryocytic-granulocytic myelosis — CMGM — since neutrophilic granulopoiesis is also apparently neoplastic and both cell lineages showed a complete differentiation to mature forms. CMGM should be separated from the chronic granulocytic leukemia — CGL — which consists of only a single line proliferation. The incidence of CGL in our total of 1,083 patients was 25%. Both entities are included in chronic myeloid leukemia — CML — because of the demonstration of the Philadelphia chromosome in the hematopoietic cells of these two groups of patients. Primary or idiopathic thrombocythemia has to be differentiated from CMGM since there is no evidence for malignancy of the granulocytic series.Professor Büngeler, meinem verehrten Lehrer, widmen wir diese und die folgenden gedanklich verknüpften Arbeiten zu seinem 80. Geburtstag     

Histomorphometry of bone marrow biopsies in chronic myeloproliferative disorders with associated thrombocytosis - features of significance for the diagnosis of primary (essential) thrombocythaemia

Summary A histomorphometric analysis was performed on trephine biopsies of the bone marrow in 55 patients with chronic myeloproliferative disorders (CMPDs) and marked thrombocytosis (platelet count exceeding 600 × 10⁹/l). This study aimed at discriminating primary (essential) thrombocythaemia (PTH) from the various other subtypes of CMPDs presenting with thrombocytosis. Following the diagnostic requirements postulated by the Polycythemia-vera-Study-Group for PTH and polycythaemia vera rubra (P.vera) and the generally accepted criteria for the establishment of chronic myeloid leukaemia (CML) and agnogenic myeloid metaplasia (AMM), our cohort of 55 patients was divided into the following subgroups: CML (16 cases), P.vera (11 cases), AMM (13 cases) and finally PTH (15 cases). Histomorphometric measurements revealed that PTH was distinguishable from the other subtypes of CMPDs with respect to several histological variables: patients with PTH had a normal amount of neutrophilic granulo- and erythrocytopoiesis as well as a non-increased content of reticulin (argyrophilic) fibers in contrast to the findings in CML, P.vera and of course AMM. Moreover, sizes of megakaryocytes and their nuclei were significantly greater in PTH and internalization of haematopoietic cells (emperipolesis) was more frequently encountered in comparison with the other subtypes of CMPDs. Deviation of the circular perimeter of megakaryocyte shape was most prominently expressed in CML and AMM, and consequently generated an increased number of a-nuclear cytoplasmic fragments. In contrast to this feature aberration of the nuclei from a circular outline occurred in a less pronounced way in CML, but was excessive in P.vera, AMM and PTH. Our morphometric evaluation demonstrates that certain histological features may serve as a valuable aid in discriminating PTH from the other occasionally thrombocythaemic subtypes of CMPDs.Supported by a grant from the Moritz Foundation, Cologne, Federal Republic of Germany     

Chronic myeloproliferative disorders (CMPD)

The wide clinical range of CMPD can be understood as leukaemia of pluripotent stem cells according to the pathogenic concepts reviewed above. Blastic metamorphoses of CMPD are regressions to a more primitive level of cellular differentiation. The predominant proliferative cell line characterizes the classical entities of PV, PT and CML, and their different prognoses. Pure erythrocytic and megakaryocytic proliferations are more compatible with sustained physiologic bone marrow functions than granulocytic proliferations. The combinations of granulocytic and megakaryocytic growth are especially prone to develop MF/OMS, in which participation of immune reactions, of granulocytic and of platelet factors is probable. An etiologic role for ineffective thrombocytopoiesis is supported by experimental as well as by histologic evidence. Myelofibrosis and osteomyelosclerosis may have similar causes, but develop independently. The prevalence of the female sex among thrombocythaemic patients was proven statistically also for the increase of giant type megakaryocytes in the form of clusters in the bone marrow, and for longer median survival of females in CMPD, especially when there is megakaryocytosis in the bone marrow. It is assumed that females may be better protected against the detrimentous effects of abnormal platelet production. An arbitrary classification according to haematologic and histologic criteria was applied to PV, PT and CML, and groups with typical and atypical haematologic and histologic signs were distinguished. The latter cannot be separated from each other by their various haematologic manifestations, but by histology and their different propensity to progress into more immature and/or fibrotic stages. Three major groups are characterized by histology: mixed granulocytic-megakaryocytic myelosis with giant megakaryocytic clusters, a similar variant with diffuse distribution of giant megakaryocytes, and immature and/or pleomorphic megakaryocytic myelosis. Transitions from each of these groups have been observed as well as transitions from each of the typical CMPD-entities into these less typical forms. CML, frequently accompanied by dwarf-megakaryocytes, often develops into pleomorphic megakaryocytic or blastic myelosis. Blastic dedifferentiation and myelofibrosis manifest themselves as closely related end stages, to which principally all groups proceed after a longer or shorter period of time, modified by the proliferating cell lines in each group. Clinical, experimental and histologic evidence of this natural history has been reviewed, with special emphasis on the re-evaluation of technically optimal bone marrow biopsies of untreated patients.(ABSTRACT TRUNCATED AT 400 WORDS)     

Polycythemia vera

Summary Clinical and morphological studies including light microscopy, electron microscopy and karyotyping of the bone marrow, were performed on a total of 164 patients with polycythemic conditions. A final diagnosis was obtained from clinical findings and histopathology of plastic embedded core biopsies of the bone marrow including sequential examinations. 51 patients revealed a secondary polycythemia whereas 113 displayed polycythemia vera (P. vera). In this last group 83 cases have persisting P. vera. 30 showed a transgression towards chronic myeloid leukemia with or without accompanying myelofibrosis — osteomyelosclerosis (so called chronic megakaryocytic-granulocytic myelosis — CMGM).The histopathology of the bone marrow in P. vera revealed consistent alterations which are useful in distinguishing this disorder from secondary polycythemia (SP) and CMGM: depletion of iron storage, increased neutrophilic granulopoiesis but no gross atypia in maturation, polymorphism of megakaryocytes with conspicuous giant forms and dilatation and increased branchings of venous sinusoids. Electron microscopic findings were in agreement and showed further abnormalities of cytological maturation in the erythrocytic and granulocytic lineage. Cytogenetic studies in 27 non-treated patients with P. vera revealed the Philadelphia chromosomes in 2 cases, whereas in SP only minor chromosomal anomalies have been encountered in a few patients.It is concluded that histopathology of trephine biopsies of the bone marrow is an invaluable aid to establish a correct diagnosis, differentiating P. vera from the other potentially polycythemic disorders and helping to detect a possible progression towards leukemia at an early stage. Cytogenetic investigations may show early structural and numerical abnormalities of the karyotype and possibly precede a presumptive transgression towards myeloid leukemia (CMGM). A simultaneously performed histological and chromosomal examination of bone marrow samples is therefore desirable in each case of a polycythemic condition.Supported by the Deutsche Forschungsgemeinschaft (grant Ge 121/19)     

The impact of megakaryocyte proliferation for the evolution of myelofibrosis

Summary A histological study on sequential bone marrow biopsies in patients with chronic myeloid leukaemia (CML) was performed. We wished to answer the question as to whether a different content of megakaryopoiesis in the bone marrow of CML patients has a prognostic significance for the development of myelofibrosis during the course of disease. In addition, the significance of possible changes in the quantity of megakaryopoiesis in this process was assessed. In 186 patients who had no fibre increase at first diagnosis, the rate of subsequent myelofibrosis varied from 19% for the common or granulocytic subtype (CML.CT) to 40% for patients with features of megakaryocytic increase (CML.MI). No significant differences were found either in the rapidity of progression to fibrosis or in the final rate of osteomyelosclerosis. Whereas in CML.MI most patients (75%) showed an increase of fibres only, this was accompanied by an additional increase of megakaryocytes in CML.CT, changing the histological pattern from CML.CT to MI or MP, respectively. The data therefore revealed a correlation between fibre increase and subtyping of CML as suggested by the Hannover classification of chronic myeloproliferative diseases. Subtypes of CML with megakaryocytic increase could be shown to present a pre-myelofibrotic stage of disease and may therefore be conceived as a particular pathway of acceleration.     

Increased incidence of monoclonal B-cell infiltrate in chronic myeloproliferative disorders.

A total of 106 trephine biopsy specimens with clinical, laboratory and pathology findings corresponding to chronic myeloproliferative disorders (CMPD) were analyzed to reveal the nature of the lymphoid infiltrate in the bone marrow. Histological investigation in 31 chronic myeloid leukemia (CML), 29 CMPDs not otherwise specified (CMPD-NOS), 28 essential thrombocytosis (ET), 15 polycythemia vera (PV) and three chronic eosinophilic leukemia/hypereosinophilic syndrome (CEL/HES) exhibited in 32% various amounts of lymphocytic infiltrate of sparsely to moderately diffuse or nodular types in the bone marrow, but the reactive or coinciding lymphomatous nature could not be revealed by histology alone in the majority of cases. PCR analysis of the immunoglobulin heavy chain (IgH) gene rearrangement was successfully performed in 81 out of the 106 DNA specimens extracted from formol-paraffin blocks. Out of the 81 samples with good-quality DNA, 18 gave a single or double discrete amplification band(s), which was reproducible only in four specimens. Sequencing finally proved monoclonal B-cell population of both pre- and postfollicular origin in all four samples (5%), one CML and three CMPD-NOS. Detailed clinical and pathological investigations indicated overt B-cell malignant lymphoma with clonal relationship to the CMPD in two out of these four patients. We conclude that detailed molecular analysis of IgH gene rearrangement in bone marrow samples of CMPD patients is needed to identify the true monoclonal B-cell infiltration, which-even without overt malignant lymphoma-may occur in this group of disorders.Modern Pathology (2004) 17, 1521-1530, advance online publication, 16 July 2004; doi:10.1038/modpathol.3800225.     

Chronic myeloproliferative disorders in bone marrow biopsies

This Diagnostic Seminar intends to announce that CMPDs can be classified from BMB histologically by a rather simple system, which can be applied by interested histopathologists successfully. The rationale of this classification is to stay within the groups of diseases which are outlined by clinical findings including the peripheral blood and bone marrow smears. The concept of traditional classification as given by the WHO and textbooks, however, has to be revised as follows (1) Primary diseases of CMPDs must be distinguished from advanced disorders. Primary diseases are CML, P. vera, Thrombocythemia, CMGM, and unclassifiable CMPD. (2) Idiopathic, primary myelosclerosis of the bone marrow is a reactive feature consecutive to neoplastic transformation of hematopoiesis, i.e. myeloproliferation. (3) Advanced disorders comprise (3.1.) excess of blasts and blast crisis, and (3.2.) early myelosclerosis, myelosclerosis and myelofibrosis, advanced myelofibrosis. Advanced disorders are designated by a composed term classifying them among the groups of primary disease and specifying the advanced stage by a suffix, so that the underlying disease remains coining the term, even in unclassifiable cases in which only CMPDs can be applied. (4) The CML group must be subtyped into CML of common type versus that with increase or predominance of megakaryocytes. By this system of classification, it seems possible to classify and type the spectrum of variations occurring among CMPDs to a satisfying result.     

Activating FLT3 mutations are detectable in chronic and blast phase of chronic myeloproliferative disorders other than chronic myeloid leukemia

FLT3 gene mutations, either internal tandem duplication (ITD) or D835 point mutations, have been studied extensively in acute myeloid leukemia and myelodysplastic syndrome (MDS). Little is known about FLT3 mutations in chronic myeloproliferative diseases (CMPDs) or their relationship with V617F JAK2 mutations. We analyzed bone marrow samples from 142 patients with Philadelphia (Ph) chromosome- CMPD or CMPD/MDS and from 119 patients with Ph+ chronic myeloid leukemia (CML) using a multiplex polymerase chain reaction assay. FLT3 mutations, 11 ITD and 2 D835, were detected in 13 (9.2%) patients with CMPD or CMPD/MDS, 7 in blast phase and 6 in chronic phase. Analyses for JAK2 mutations in 11 of 13 cases were all negative. By contrast, no FLT3 mutations were detected in CML, including 108 chronic and 11 blast phase cases. FLT3 mutations occur in approximately 10% of CMPD and CMPD/MDS but are not observed in JAK2+ CMPD or in CML.     

Thrombozytose versus Thrombozythämie – zur Differentialdiagnose des erhöhten Plättchenwertes

Differentiation of an elevated, repeatedly determined platelet count (> or =500x10(9)/l) includes the discrimination between reactive causes generated by a variety of underlying conditions and a neoplastic myeloproliferative disorder (CMPD). In addition to clinical findings, the evolution of laboratory data during follow-up and histology of the bone marrow exerts a significant diagnostic impact. Characteristic features are not only expressed by hematopoiesis, but also by the myeloid stromal compartment. While the megakaryocyte-rich subtype of chronic myeloid leukemia (CML) and the 5q(-) syndrome (MDS) are dominated by abnormal micromegakaryocytes, in polycythemia vera (PV) this cell lineage reveals a pleomorphous appearance. In essential thrombocythemia (ET), a prevalence of giant megakaryocytes with deeply lobulated (staghorn-like) nuclei may be encountered. A clear-cut discrimination of ET from early (hypercellular) stages of idiopathic (primary) myelofibrosis (IMF) presenting with thrombocythemia becomes possible, provided the conspicuous atypical features of megakaryopoiesis characterizing the latter entity are taken into account. Moreover, CML displays a predominance of the granulocytic lineage whereas PV shows a panmyelosis or trilineage proliferation, involving erythropoiesis, in particular. In contrast, erythropoiesis is markedly reduced in CML and to a lesser degree also in IMF. In CMPDs extreme values of iron deposits may be found, ranging from a total lack (PV) to minor amounts (CML) and a normal staining reaction (ET). Similar results are exhibited regarding reticulin fibrosis, which is usually not present in ET, rarely observed in PV and detectable to a variable degree in CML and IMF.     

Chronic megakaryocytic-granulocytic myelosis — An electron microscopic study including freeze-fracture

Summary In 5 patients with chronic megakaryocytic-granulocytic myelosis (CMGM) bone marrow specimens were studied by electron microscopy to investigate possible abnormalities of the granulocytic cell lineage. Thin sections were compared with freeze-fracture replicas to elucidate further aspects of leucocyte cytology. The atypia exhibited in these cells (eosinophils, basophils and neutrophil granulocytes) consisted mostly of a disorganization of granulopoiesis with hyper- and hypogranulation, a pathological increase in the number of nuclear blebs and a maturation asynchrony sometimes leading to Pelger-like cell forms. Moreover, a presumptive stem cell was demonstrated in the erythopoietic and granulocytic cell lines resembling CFU cells. In conclusion, granulopoiesis in CMGM exhibited abnormalities as generally observed in chronic myelogenous leukaemia. When considered with our previous finding of malignancy in megakaryopoiesis, CMGM has to be classified as a myelosis of mixed cellularity.Abbreviations CMGM Chronic megakaryocytic-granulocytic myelosis - CGL Chronic granulocytic leukaemia - MF Osteomyelofibrosis - RER Rough surfaced endoplasmic reticulum Supported by the Deutsche Forschungsgemeinschaft, grant Ge 121/15     

Incidence of pulmonary hypertension in patients with chronic myeloproliferative disorders

STUDY OBJECTIVE: To assess the incidence of pulmonary hypertension (PH) in patients with chronic myeloproliferative disorders (CMPD). METHOD: Twenty-seven patients with a diagnosis of CMPD were included in the study. Patients were excluded if they had a secondary cause of PH. Diagnosis of PH was established if right ventricular systolic pressure (RVSP) by transthoracic echocardiography (TTE) was >35 mmHg. RESULTS: Diagnosis of PH was established in 14 out of 27 patients. Two patients were excluded from analysis because of poor ejection fraction on TTE, resulting in a final diagnosis of PH in 12 of 25 (48%) patients. Of these 25 patients, seven of nine with essential thrombocytosis (ET), five of 14 with polycythemia vera (PV), and 0 out of two with chronic myeloid leukemia (CML) had PH. All patients were asymptomatic at the time of their most recent visit. There was no relationship between PH and age at diagnosis, duration of disease, platelet count and hematocrit at diagnosis or during follow-up, both for the entire cohort or for specific diagnosis of ET or PV. CONCLUSION: Pulmonary hypertension appears to be common in patients with CMPD. Further studies are needed to evaluate the impact of treatment on PH and long-term survival in these patients.     

Megakaryocytes carry the fused bcr-abl gene in chronic myeloid leukaemia: a fluorescence in situ hybridization analysis from bone marrow biopsies

Histological examination of bone marrow biopsies shows that about one-third of chronic myeloid leukaemia (CML) patients exhibit an increase of megakaryocytes. The megakaryocytic predominance may be so striking that differentiation from other chronic myeloproliferative disorders (CMPD) may be difficult in some CML patients. Megakaryocytes in CML are clonal as demonstrated by loss of glucose-6-phosphate dehydrogenase isoenzymes. The Ph translocation, fusing the abl and bcr genes on chromosomes 9 and 22, however, obviously occurs as a second step in tumour development. So far, the Ph translocation has not been assigned explicitly to megakaryocytes. The question is whether the megakaryocytic cell lineage could harbour the bcr/abl fusion in those CML cases with striking proliferation of megakaryocytes but lack this genetic defect in cases with normal or decreased megakaryocyte counts. We therefore performed triple-colour fluorescence in situ hybridization (FISH) for portions of the bcr and abl genes flanking the breakpoint in CML in paraffin sections of CML cases with normal and with increased numbers of megakaryocytes. This method allows identification of the bcr/abl fusion in single, morphologically intact cells, whereas conventional cytogenetics requires lysis and thus destruction of the cell. Among the 21 CML patients examined by FISH, 10 were informative for bcr and abl genes and displayed distinct hybridization signals within nuclei of bone marrow cells. Besides the granulopoietic cells, megakaryocytes of all those patients (4 without and 6 with varying grades of megakaryocytic increase) displayed bcr/abl fusion signals indiciative of a Ph translocation. The lack of hybridization signals in the remaining 11 cases indicates that this technique is not of value diagnostically and should be reserved for scientific questions. Positive controls consisted of conventional chromosome preparations from bone marrow aspirates demonstrating the Ph chromosome in all patients examined, and negative controls of paraffin sections of bone marrow biopsies from non-CML patients. These showed no fusion signals in bone marrow cells, including megakaryocytes, using FISH. Our results demonstrate clearly that not only the transforming event but also the Ph translocation leading to the bcr/abl fusion happens prior to the differentiation of the pluripotent stem cell into different myeloid lineages. The megakaryocytic proliferation evident in some CML cases is probably a consequence of the disease progress.     

Genetic analysis of chromosome 13 deletions in BCR/ABL negative chronic myeloproliferative disorders

Chromosomal deletions of band 13q14 occur recurrently in BCR/ABL negative chronic myeloproliferative disorders (CMPD), including myelosclerosis with myeloid metaplasia (MMM), polycythemia vera (PV), essential thrombocythemia (ET), juvenile chronic myeloid leukemia (JCML), and the so-called BCR/ABL ^? chronic myeloid leukemia (CML). The RB1 tumor suppressor locus, mapping to 13q14, has long since been hypothesized as the important gene. In this report, we have determined the frequency of 13q14 deletions at the molecular level in a large panel of BCR/ABL ^? CMPD at different disease stages and performed a detailed genetic analysis of gross rearrangements/deletions and point mutations of the RBI gene in these disorders. Our data show that molecular deletions of 13q14 are detected in a relatively large fraction of BCR/ABL ^? CMPD (38%), that they appear to be more frequent in MMM than in other BCR/ABL ^? CMPD, and that they may be present at diagnosis or occur during blastic evolution of the neoplasia. The RBI gene displayed a germline configuration in all BCR/ABL ^? CMPD tested, suggesting that 13q14 deletions in these disorders affect a tumor suppressor locus distinct from RB1.     

Changing patterns of histological subgroups during therapy of Ph1+ chronic myelogenous leukaemia

AIMS: Bone marrow histopathology reveals a striking heterogeneity at diagnosis of Philadelphia chromosome positive (Ph1+) chronic myelogenous leukaemia (CML). Based on semiquantitative evaluations of the number of megakaryocytes and the content of fibres, various histological subtypes have been postulated. However, little information exists on whether these groups represent stable categories of the different classification systems and whether therapeutic regimes exert any influence on the putative shift of histological patterns. METHODS AND RESULTS: A retrospective clinicopathological study was performed on 396 bone marrow biopsies derived from 173 patients. There were at least two representative trephines taken at diagnosis and at median intervals of 16 months. Processing of the specimens involved immunostaining with CD61 (megakaryopoiesis) and Ret40f (erythropoiesis) and Gomori's silver impregnation technique. Based on morphometric analysis and in accordance with the general appearance of bone marrow histology three different histological subtypes were distinguished. These consisted of a granulocytic (51 patients), a predominantly megakaryocytic (73 patients) and a myelofibrotic pattern (49 patients). Follow-up biopsies revealed that a significant transition of histological groups occurred and that, independently of treatment modalities, the myelofibrotic category was associated with an unfavourable prognosis. Of the 124 patients without myelofibrosis at onset, 42% later transformed into the myelofibrotic subtype. However, these patients showed no prevalence of either a pre-existing granulocytic or megakaryocytic growth. Myelofibrotic changes were significantly associated with interferon (IFN) and busulfan (BU) therapy. On the other hand, a transition of a myelofibrotic into a nonfibrotic subtype was detectable in 17 of the 49 patients under study and related to hydroxyurea (HU) treatment. CONCLUSIONS: Histological classification systems of bone marrow features in CML do not represent stable patterns, but may be significantly altered by therapy, in particular IFN and HU.     

DNA analysis to aid in the diagnosis of chronic myeloproliferative disorders.

Diagnosing chronic myeloproliferative disorders (CMPD) can be difficult because of overlap and possible transitions between the different conditions and their similarity to reactive myeloproliferations. DNA analysis was applied to improve differentiation of CMPDs. All subtypes of CMPD analyzed, including chronic myeloid leukemia, agnogenic myeloid metaplasia, polycythemia vera, and essential thrombocythemia, had in common that granulocytes and bone marrow cells were clonal in origin, as shown by X chromosome-linked DNA polymorphism in conjunction with methylation patterns (n = 32). Reactive myeloproliferations, by contrast, showed polyclonal inactivation patterns. Clonality could not distinguish CMPD from cases of myelodysplastic syndrome because the latter (n = 7) also exhibited clonal hematopoiesis. Because of their clonal origin, peripheral granulocytes were used in all cases (n = 201) to detect bcr gene rearrangement. Despite possible morphologic overlap between different types of CMPD, bcr gene rearrangement was specific for chronic myeloid leukemia and could be applied to differentiate chronic myeloid leukemia from other CMPDs in cases of equivocal morphologic diagnosis. Chronic myeloproliferative disorders represent clonal hemopoietic diseases that probably have specific underlying genetic defects. Thus DNA analysis can aid substantially in the differential diagnosis of CMPD.     

Osteomyelofibrosis/-sclerosis: A histological and cytogenetic study on core biopsies of the bone marrow

Summary A combined histological and cytogenetic study was performed on the bone marrow in 33 patients with overt osteomyelofibrosis/-sclerosis (MF/OMS) and so called agnogenic myeloid metaplasia including blast crisis. Histopathology of the plastic embedded samples of bone marrow showed an abnormal proliferation of megakaryopoiesis with conspicuous atypias of growth and maturation in addition to a neoplastic neutrophilic granulopoiesis, particularly in the early stages of MF. Thus a biphasic population of neoplastic hematopoiesis is postulated and this lesion is called chronic megakaryocytic-granulocytic myelosis (CMGM) with myelofibrosis — CMGM stage III — or with osteomyelosclerosis — CMGM stage IV. Initiation of fibrillogenesis, the most striking alteration of this disorder, is partially attributed to disorganization of megakaryopoiesis with abnormal proliferation and clustering around the sinuses and intraluminal growth, with subsequent obliteration of the vascular compartment. Cytogenetic evaluation demonstrated the Philadelphia chromosome (Ph'-chromosome) in 93% of CGL and in 67% of MF/OMS, including cases with blast crisis. Unlike CGL and MF/OMS where a Ph'-chromosome is common, myelofibrosis of non-neoplastic origin and AML displayed no Ph'-chromosome. Further aberrations such as aneuploidy involved the C/D group chromosomes predominantly and were especially prominent in blast crisis (about 50%) with no significant differences in CGL and MF/OMS or in AML. Our results of chromosomal analysis, evaluated in close context with histopathology, show no fundamental differences between CGL and myeloproliferative disorders of mixed cellularity, i.e., chronic megakaryocytic-granulocytic myelosis (CMGM). For this reason the terminal stages of fibrotic and osteosclerotic lesions belong into these categories of CMGM or CGL respectively. In conclusion MF/OMS are final stages or subtypes of CML, carrying the same chromosomal marker and demonstrating remarkable atypias of the hematopoietic tissue suggestive of malignancy. The fibrotic/ osteosclerotic alteration itself is thought to represent a secondary nonneoplastic feature.Supported by the Deutsche Forschungsgemeinschaft (grant GE 121/20)