Histopathology in the diagnosis and classification of acute myeloid leukemia, myelodysplastic syndromes, and myelodysplastic/myeloproliferative diseases.

In spite of the impressive advances in the area of molecular pathology, bone marrow morphology remains the diagnosis cornerstone to identify the various subtypes of myeloid neoplasms. Morphological examination of the bone marrow requires both bone marrow aspirate and bone marrow trephine biopsy. Immunohistochemistry of bone marrow biopsy with markers reactive in paraffin-embedded tissues represents a powerful diagnostic tool; its results can be easily correlated with those obtained by other techniques such as flow cytometry and genetic analysis, and above all, the clinical findings. The role of the bone marrow biopsy will be particularly stressed in this review article. Particular emphasis is being given to the correct identification of cases of myeloid neoplasms associated with myelofibrosis and for which the bone marrow biopsy represents the only available diagnostic mean. Moreover, the often low cellular yield of the bone marrow aspirate in these cases may also be insufficient to obtain adequate cytogenetic information. Such cases include two subtypes of acute myeloid leukemia which typically cause diagnostic difficulties: acute megakaryoblastic leukemia and acute panmyelosis with myelofibrosis (acute myelosclerosis). Acute myeloid leukemia with multilineage dysplasia, therapy-related myelodysplastic syndrome/therapy-related acute myeloid leukemia and de novo myelodysplastic syndromes (MDS) will also be discussed. The value of bone marrow biopsy in this group of disorders is generally well established. In MDS, in particular, bone marrow biopsy may help in confirming a suspected diagnosis by excluding reactive conditions in which dyshematopoietic changes may also be observed. It can increase the diagnostic accuracy and helps in refining the IPPS risk evaluation system. Among the alterations detected by bone marrow biopsy, a prognostically important finding is the presence of aggregates or clusters of immature myeloid precursor cells (myeloblasts and promyelocytes). These can also be identified by immunohistochemistry with CD34, an antigen expressed in progenitor and early precursor marrow cells, which can be used to demonstrate pathological accumulations of blasts in aggressive subtypes of myeloid neoplasms. Immunohistologic analysis is especially helpful in cases of MDS with fibrosis and cases with hypocellular marrows (hypoplastic MDS). In both of these variants, the presence of reticulin fibrosis or fatty changes in the bone marrow can make accurate disease characterization very difficult or impossible using bone marrow aspirates. Finally, the important group of the myelodysplastic/myeloproliferative disorders can only be accurately categorized by a careful multiparametric approach in which the bone marrow biopsy exerts a pivotal role.     

Clinical impact of dysplastic changes in acquired aplastic anemia: A systematic study of bone marrow biopsies in children and adults

Aplastic anemia (AA) is a rare disorder characterized by suppression of bone marrow function, which can progress to myelodysplastic syndrome (MDS) or to acute myeloid leukemia (AML). To determine if there are characteristics in bone marrow biopsies in children and adults previously diagnosed with acquired AA, which could predict progression to MDS, we evaluated 118 hypocellular bone marrow biopsies from adults (76 patients) and children (42) diagnosed initially with acquired AA previously to any treatment. Histology was reviewed according to a detailed protocol including Bennett and Orazi criteria for hypocellular myelodysplastic syndrome (h-MDS) and Bauman et al. criteria for refractory cytopenia of childhood (RCC). Twelve patients (10.2%; 6 children and 6 adults) progressed to MDS after a median time of 56 months. Criteria described by Bennett and Orazi suggestive of h-MDS in bone marrow biopsies were detected in 16 cases (13.5%; 8 adults and 8 children), and none in patients that progressed to MDS/AML. Twenty adults' biopsies (26.3%) had the histological criteria used for the diagnosis of pediatric RCC, and none showed MDS/AML evolution. Ten children (23.8%) were reclassified morphologically as RCC, and only one progressed to MDS. In this population with acquired aplastic anemia (AAA), no histological/immunohistochemical (H/IHC) bone marrow findings could discriminate patients with higher risk for myeloid clonal progression, which questions the diagnosis of h-MDS/RCC based only on the finding of dysplasia in the cases without increased blasts and/or the characteristic genetic abnormalities.     

Different effect of granulocyte colony-stimulating factor or bacterial infection on bone-marrow cells of cyclophosphamide-treated or irradiated mice

In the present study, the effect of treatment with granulocyte colony-stimulating factor (G-CSF) on cellular composition of the bone marrow and the number of circulating leucocytes of granulocytopenic mice, whether or not infected with Staphylococcus aureus, was assessed. With two monoclonal antibodies, six morphologically distinct cell populations in the bone marrow could be characterised and quantitated by two-dimensional flow cytometry. Granulocytopenia was induced by cyclophosphamide or sublethal irradiation. Cyclophosphamide predominantly affected the later stages of dividing cells in the bone marrow resulting in a decrease in number of granulocytic cells, monocytic cells, lymphoid cells and myeloid blasts. G-CSF administration to cyclophosphamide-treated mice increased the number of early blasts, myeloid blasts and granulocytic cells in the bone marrow, which indicates that this growth factor stimulates the proliferation of these cells in the bone marrow. During infection in cyclophosphamide-treated mice the number of myeloid blasts increased. However, when an infection was induced in cyclophosphamide and G-CSF-treated mice, the proliferation of bone-marrow cells was not changed compared to that in noninfected similarly treated mice. Sublethal irradiation affected all bone-marrow cell populations, including the early blasts. G-CSF-treatment of irradiated mice increased only the number of myeloid blasts slightly, whereas an infection in irradiated mice, whether or not treated with G-CSF, did not affect the number of bone-marrow cells. Together, these studies demonstrated that irradiation affects the early blasts and myeloid blasts in the bone marrow more severely than treatment with cyclophosphamide. Irradiation probably depletes the bone marrow from G-CSF-responsive cells, while cyclophosphamide spared G-CSF responsive cells, thus enabling the enhanced G-CSF-mediated recovery after cyclophosphamide treatment. Only in these mice, bone marrow recovery is followed by a strong mobilisation of mature granulocytes and their band forms from the bone marrow into the circulation during a bacterial infection.     

An autopsy case of myelodysplastic syndrome (MDS): diagnostic problems between MDS and the other haematopoietic disorders including acute myelofibrosis

We report an autopsy case of myelodysplastic syndrome (MDS) in a 35-year-old male, who presented with pancytopenia and bleedings. Bone marrow specimens disclosed myelofibrosis and hypercellular marrow with more than 60% atypical erythroblasts in the bone marrow cells. Type I or type II blasts were less than 10% of the peripheral blood and bone marrow cells during the clinical course. At autopsy, infiltration by myeloid and erythroid cells and megakaryocytes was noted in the liver, spleen and lymph nodes. According to the FAB classification, this case might be classified into refractory anemia with excess of blasts (RAEB) or RAEB in transformation. However, the remarkable neoplastic proliferation of three haematopoietic cell lines also indicates acute myeloproliferative disorder such as acute myelofibrosis or acute panmyelosis.     

Myelodysplastisches Syndrom (MDS)

Myelodysplastic syndromes (MDS) are a heterogenous group of clonal stem cell disorders which generally occur in older adults but may also affect children. Primary MDS should be distinguished from secondary MDS associated with antineoplastic or immunosuppressive therapy (t-MDS), exposure to toxic compounds, or genetic disorders. The establishment of a neoplastic clone is reflected by dysplastic features and impaired function which may affect all three hematopoietic cell lineages. The ineffective hematopoiesis which causes bone marrow failure is accompanied by peripheral blood cytopenia and is considered to result from increased apoptosis, at least in the less advanced MDS stages. The elucidation of the molecular pathogenesis of MDS has provided evidence that chromosomal abnormalities are present in about 50% of patients with primary MDS. They include numerical aberrations such as monosomy 5 or 7, trisomy 8, loss of the Y-chromosome and structural abnormalities such as deletion of the long arm of chromosome 5 (5q-syndrome), 7, or 8. Based on the percentage of blasts (<5%, 5-20%, 20-30%) and the presence of >15% ringed sideroblasts for marrows with <5% blasts, the French-American-British (FAB) classifies MDS into 4 morphologic categories: refractory anemia (RA), refractory anemia with excess of blasts (RAEB), refractory anemia with excess of blasts in transformation (RAEB-t), and refractory anemia with ringed sideroblasts. The fifth morphologic type is chronic myelomonocytic leukemia characterized by peripheral blood monocytosis (>1x10(9)/l). However, a modification of this classification will be proposed by the World Health Organization, with the intention of lowering the threshold for the diagnosis of AML from 30% to 20% blast cells. In patients presenting with cytopenias suggesting impaired hematopoiesis, the initial diagnosis depends mainly on the cytological evaluation of bone marrow and blood smears and the histological findings of trephine bone marrow biopsy. In a retrospective analysis we evaluated the occurrence of the distinct FAB-categories as percentage of the total number of MDS cases diagnosed at the Institute of Pathology of the University of Freiburg. A total of 63% fullfilled the criteria of RA/RARS, 17% of RAEB, 14% of RAEB-t, and 6% of CMML. A fibrotic variant of MDS was observed in 7.67% of all cases, ranging from 2.34% in RA up to 15. 42-15.84% in the categories which did not show significant differences with regard to myelofibrosis. The histologic evaluation of a trephine bone marrow biopsy is of critical importance for the evaluation of fibrotic or hypocellular MDS since these patterns are not reflected by the cytological examination. The combined cytological and histological diagnosis of bone marrow and peripheral blood is a reliable tool for the initial diagnosis of MDS. In addition, cytogenetic and molecular analysis should be performed. Presently, the risk of leukemic transformation is evaluated using the International Prognostic Scoring System for MDS, which is the sum of the scores of bone marrow blasts, karyotypes and cytopenia. In the context of clinical trials therapeutic modalities should be considerd according to the age and the general performance state and the prognostic scores of individual patients.     

Trisomy 22--a new abnormality found in acute leukemia characterized by eosinophilia and monocytoid blasts expressing immature differentiation antigens

Bone marrow cells from three patients with acute myeloid leukemia, with marrow eosinophilia and monocytoid blasts, showed a new nonrandom chromosomal abnormality, trisomy 22. In two patients the classification of leukemia was M4 and in the third patient M2 (FAB classification). Pretreatment bone marrows in these patients revealed 31%, 30%, and 4% eosinophils, respectively. Blast cells isolated from peripheral blood were Ia-positive and expressed immature monocyte lineage antigens (U26, U28, U48) in 26%-92% of cells. All three patients had a population of bone marrow cells characterized by an extra chromosome #22. One patient also had inversion of chromosome #16. Trisomy 22, bone marrow eosinophilia, and monocytoid blasts displaying early monocyte differentiation antigens may represent a new subgroup of patients with acute myeloid leukemia.     

Distinction between aleukaemic prodrome of childhood acute lymphoblastic leukaemia and aplastic anaemia.

AIMS: To document the features of the so-called aplastic presentation of childhood acute lymphoblastic leukaemia (ALL) and to determine whether this prodrome can be distinguished from aplasia. METHODS: The peripheral blood and bone marrow appearances of all cases of childhood ALL presenting in one health region of England in 13 years and eight months were reviewed. All cases presenting with cytopenia without circulating blasts and marrow aspirates with no infiltrate of blasts were studied in detail. RESULTS: Four of 305 (1.3%) children presented in this way. All four had reticulin fibrosis and increased cellularity in all or part of the marrow biopsy specimen. All were girls. Three had common and one surface membrane immunoglobulin positive ALL. Reassessment of this prodrome, by combining the features of four previously reported series of similar cases with the present one, highlighted the female preponderance (19 of 22 cases), bone marrow fibrosis (10 of 11 evaluable cases), prominent bone marrow lymphocytes (14 of 22 cases) and temporary recovery (all 12 evaluable cases). Six of 14 evaluable cases had bone marrow biopsy specimen appearances of apparently uniform hypocellularity, but only one of these did not have fibrosis. CONCLUSIONS: If, in addition to an aspirate, a bone marrow trephine biopsy is carried out the prodrome can be distinguished from aplasia in most cases. The similarity of this prodrome to aplastic anaemia is merely superficial. Clinicians and morphologists may fail to appreciate the implications of this mode of presentation if the term "aplastic" continues to be used to describe this aleukaemic prodrome of ALL.     

Prediction of impending blast cell transformation in chronic granulocytic leukaemia

Bone marrow trephine biopsy specimens from 24 patients with chronic granulocytic leukaemia were studied to identify bone marrow changes that suggest incipient or impending blast transformation. In the chronic phase of chronic granulocytic leukaemia, blasts and promyelocytes were seen predominantly in the paratrabecular and perivascular regions, while myelocytes, metamyelocytes and segmented polymorphs were seen predominantly in the central intertrabecular marrow space. The patients were divided into two equal groups according to the degree of perivascular and paratrabecular infiltration: those with minimal (one to three layers of blasts and promyelocytes) and those with marked (four to eight layers of blasts and promyelocytes) infiltration. Ten of the 12 patients in the former group did not develop blast transformation and remained in the chronic phase during a 32- to 84-week follow-up period, whereas nine of the 12 patients in the latter group developed blast transformation, with six undergoing transformation within the first 26 weeks. These findings suggest that the histomorphological pattern of bone marrow changes in chronic granulocytic leukaemia may be useful in recognizing a subset of chronic granulocytic leukaemia patients undergoing blast transformation in the ensuing 6 months.     

Prominent gelatinous bone marrow transformation presenting prior to myelodysplastic syndrome: a case report with review of the literature

Gelatinous bone marrow transformation (GMT) is a rare disorder characterized by the presence of fat cell atrophy, loss of hematopoietic cells, and deposition of extracellular gelatinous materials. GMT is not a specific disease, but is strongly associated with malnutrition and drugs. Albeit extremely rare, GMT has been reported in patients with myeloproliferative disorders. Herein, we report the second documented case of hypoplastic myelodysplastic syndrome (MDS) accompanying GMT. A 73-year-old Japanese male with excellent nutrition status and no history of alcohol or drug intake was detected with pancytopenia. The initial bone marrow aspirate specimen reveled hypocellular marrow without dysplastic signs in the myeloid cells. Bone marrow biopsy demonstrated hypocellular bone marrow with prominent GMT. He received blood transfusions, however, pancytopenia continued to progress. The second bone marrow aspirate specimen showed dysplastic changes, such as pseudo-Pelger-Huët cells, hypogranular or agranular granulocytes, and megakaryocytes with multiple small nuclei. Cytogenetic study demonstrated deletion of chromosome 7. Therefore, an ultimate diagnosis of hypoplastic MDS accompanying GMT was made. Only a limited number of cases of myeloproliferative disorders with GMT have been reported. Our analysis of these cases revealed that chromosome 7 abnormality is frequently observed in this condition. Moreover, findings from the current case suggested that myeloproliferative disorders including MDS must be included in the differential diagnostic considerations of GMT patients, who have no history of malnutrition or drugs, and careful examination of the bone marrow smear specimen and cytogenetic analysis are necessary for early detection of underlying myeloproliferative disorders.     

Myelodysplastic syndrome that progressed to acute myelomonocytic leukemia with eosinophilia showing peculiar chromosomal abnormality: a case report.

Myelodysplastic syndrome is a closely related group of acquired bone marrow disorders characterized by ineffective and dysplastic hematopoiesis. These clonal disorders frequently progress to acute leukemia. Acute myelomonocytic leukemia with eosinophilia is characterized by an increase in abnormal eosinophils in the bone marrow, relatively good clinical course and inv (16) chromosomal abnormality. We experienced one case of refractory anemia with excess blasts which progressed to refractory anemia with excess blasts in transformation and finally to acute myelomonocytic leukemia with eosinophilia showing peculiar chromosomal abnormalities of der (1;7).     

5q — syndrome in a child

A boy aged 8 years, 10 months presented with refractory anemia. Bone marrow investigation revealed monolobular megakaryocytes. Cytogenetic analysis showed a clonal abnormality: 46, XY, del(5)(q14q32). This is the youngest individual ever reported with this disorder. A year after diagnosis, while on treatment with human recombinant erythropoietin, the bone marrow showed an excess of blasts. No bone marrow donor could be found. Transformation to acute myelomonocytic leukemia occurred 3 months later. In spite of intensive chemotherapy, the child died of progressive disease with massive splenomegaly and jaundice. The case illustrates that the 5q- syndrome can occur de novo in children. The outcome in this child was poor, which may reflect a difference from the adult 5q- syndrome or may possibly be related to the erythropoietin the child received.     

Chronic myelomonocytic leukemia: The role of bone marrow biopsy immunohistology.

The World Health Organization criteria for diagnosing chronic myelomonocytic leukemia (CMML) are largely based on findings observed in the peripheral blood and bone marrow aspirate. A specific diagnostic role for the bone marrow biopsy has not been adequately explored. We examined whether bone marrow biopsy supplemented by immunohistochemistry may be helpful in distinguishing CMML from cases of chronic myelogenous leukemia and atypical chronic myeloid leukemia (aCML). We immunostained 25 cases of CMML with paraffin reactive antibodies which included CD68 (KP1), CD68R (PG-M1), and CD163, and compared the results with those observed in six cases of chronic myelogenous leukemia and in three cases of atypical CML. In addition, we examined whether CD34 immunohistochemistry could be useful in separating cases of CMML with less than 10% blasts (type-1) from cases of CMML with blasts accounting for 10-19% (type-2), and cases of CMML in acute transformation to acute myeloid leukemia (blasts > or = 20%). The presence of nodules of plasmacytoid monocytes was investigated by CD123 staining. CD42b was used to highlight abnormal megakaryocytes. Our results demonstrate significant differences between the groups. CD34 analysis allowed separating CMML type-1 from type-2 and the former from CMML in acute transformation. CD123-positive plasmacytoid monocyte nodules were found only in CMML and not in the other two disease groups. Overlap between CMML and the other two groups were observed with CD68 immunostaining. CD68R was more restricted to bone marrow macrophages and monocytes than CD68, but the differences between CMML and chronic myelogenous leukemia or atypical CML were still not significant. Although CD42b immunostaining facilitated the detection of dwarf megakaryocytes often present in CMML, the distinction between those and the small forms seen in chronic myelogenous leukemia was still problematic.     

Acute panmyelosis with myelofibrosis: an entity distinct from acute megakaryoblastic leukemia.

The WHO criteria for diagnosing acute panmyelosis with myelofibrosis are somewhat distinct from those for acute megakaryoblastic leukemia. However, clinical and hematopathologic findings partially overlap. This has raised questions as to whether these are indeed separate, definable entities. To determine the potential importance of bone marrow biopsy supplemented by immunohistochemistry in distinguishing between these two conditions, we studied 17 bone marrow biopsies of well-characterized cases of acute panmyelosis with myelofibrosis (six cases) and acute megakaryoblastic leukemia (11 cases). We compared blast frequency, reticulin content, CD34 expression, and the degree of megakaryocytic differentiation of the blast cells in these two conditions. Our results demonstrate important differences. Acute panmyelosis with myelofibrosis is characterized by a multilineage myeloid proliferation with a less numerous population of blasts than acute megakaryoblastic leukemia (P<0.01). In the former condition, blasts are always positive with CD34, while in acute megakaryoblastic leukemia they express CD34 in 60% of the cases. The blasts in acute panmyelosis with myelofibrosis only rarely express megakaryocytic antigens. By contrast, acute megakaryoblastic leukemia has a significantly higher proportion of blasts expressing megakaryocytic antigens (P<0.01 with CD42b). Our results confirm that histology supplemented by immunohistochemistry permits the distinction of these conditions in routinely processed bone marrow biopsies.     

Evolution of acute leukemia in myelodysplastic syndromes: prognostic histopathological factors in a series of bone marrow biopsies

Out of 9,324 bone marrow biopsies, 250 cases of myelodysplastic syndromes (MDS) and 514 of acute non-lymphoid leukemia (AL) were collected. Twenty AL represented an evolution of MDS: the marrow had a mean cellularity of 58.5%, a mean percentage of blasts of 19% (55% of the cases had more than 10% of blasts in the marrow); only in one case (5%) benign lymphoid nodules (LN) were present. In 42 cases of MDS deceased without an evolution to overt AL, the bone marrow showed a cellularity of 60%, a mean percentage of blasts of 14% (only 29% had more than 10% of blasts); in 13 cases (31%) LN were present. Our data indicate that the percentage of bone marrow blasts is the most significant criterion for predicting an evolution to AL, although in the single case such evolution is not foreseeable. The presence of LN mostly in MDS without a leukemic progression could indicate a protective effect of NL, perhaps by means of an immunologic mechanism.     

Refractory myelodysplastic anaemias with hypocellular bone marrow.

Thirty three patients with refractory myelodysplastic anaemias (RMDA) with marrow hypocellularity were reviewed to see whether they differed from those with normocellular or hypercellular marrows. The median age was 65 years with a male:female ratio of 26:7. There were 11 cases of refractory anaemia (RA), four of refractory anaemia with ringed sideroblasts (RARS), and 18 of refractory anaemia with excess of blasts (RAEB). All presented with peripheral cytopenias, mostly pancytopenia or bicytopenia dysplasia in one or more cell lineages, and a marrow biopsy specimen with less than normal numbers of nucleated cells for the age. Twenty four patients died, including 14 of the 16 who developed acute non-lymphocytic leukaemia (ANLL). The results suggest that patients with hypocellular RMDA have a similar prognosis to those with normocellular or hypercellular marrows at presentation.     

Anti-CD34 immunoperoxidase staining in paraffin sections of acute leukemia: comparison with flow cytometric immunophenotyping.

Anti-CD34 is a monoclonal antibody that reacts with bone marrow progenitor cells and leukemic blasts, and is expressed on 30% to 50% of all acute leukemias. Detection of CD34 has previously been restricted to flow cytometric studies. To expand the utility of CD34, we immunostained 46 paraffin-embedded bone marrow specimens with acute leukemia; results were compared with flow cytometric studies. CD34 reactivity was also evaluated in nine chronic leukemia cases, 27 malignant lymphoma cases (Hodgkin's disease and non-Hodgkin's lymphoma), six normal bone marrow specimens, and three benign, hyperplastic lymph node specimens. All cases that were CD34 positive by flow cytometry (11 of 19 B-cell precursor acute lymphoblastic leukemia cases, one of six T-cell acute lymphoblastic leukemia cases, and seven of 21 acute myeloblastic leukemia cases) were also CD34 positive in paraffin sections. Both cell membrane and cytoplasmic staining was seen. The positivity percentage and fluorescence intensity by flow cytometry correlated with the estimated number of stained cells and the intensity of immunoperoxidase staining in 18 of 19 CD34-positive cases. The remaining bone marrow and lymph node cases studied were CD34 negative; prominent endothelial cell staining, however, was noted. This is the first report of anti-CD34 staining of acute leukemia in paraffin-embedded sections. In contrast to other monoclonal antibodies reactive in bone marrow paraffin sections with leukemia, anti-CD34 immunoperoxidase staining is limited to leukemic blasts and may provide useful diagnostic information when flow cytometric studies are not available.     

Acute myelomonocytic leukemia with histologic features resembling sarcomatoid carcinoma in bone marrow

We report a case of primary acute myelomonocytic leukemia involving the bone marrow that resembled sarcomatoid carcinoma. The neoplastic cells in bone marrow biopsy specimens formed cohesive-appearing clusters and cords separated by an immature fibroblastic proliferation and myxoid stroma. Blasts in the bone marrow aspirate smears formed clusters and sheets, and a subset of blasts exhibited erythrophagocytosis. Dysgranulopoiesis was also present. Lineage was confirmed by immunohistochemical analysis of formalin-fixed, paraffin-embedded tissue. The tumor cells showed strong reactivity for lysozyme, myeloperoxidase, CD45, and CD68 and were negative for keratin, S100, CD20, and CD3. The serum lysozyme concentration (110 microgram/mL) was 13 times greater than the normal value (8 microgram/mL). Cytogenetic studies performed on bone marrow aspirate material revealed a complex karyotype, including trisomy 8 and abnormalities of chromosome 11q. We report this case of acute myelomonocytic leukemia because the neoplastic cells appeared cohesive and spindled, resembling sarcomatoid carcinoma, and therefore caused diagnostic difficulty. Other monocytic neoplasms with similar resemblance to carcinoma or sarcoma have been reported in the literature, suggesting that the tendency to appear cohesive may be an inherent characteristic of neoplastic cells with monocytic differentiation.     

Acute megakaryoblastic leukemia in an infant with a novel t(1;9)(p32;q34)

We report a case of a 14-month-old girl with acute megakaryoblastic leukemia (AMKL). May-Giemsa staining of the bone marrow cells revealed the proliferation of two distinct types of blasts. One type of blasts had cytoplasmic blebs, and the other showed a lymphoblastic morphology without blebs. Both types of blasts were negative for peroxidase and esterase reactions. Electron microscopic platelet peroxidase (PPO) reaction also revealed the presence of two types of blasts. One had irregular-shaped nuclei and positive PPO reaction in the nuclear envelope and rough endoplasmic reticulum but not in the Golgi apparatus. These types of blasts were considered to be megakaryoblasts. The other had an immature phenotype with round nuclei and positive PPO reaction in the nuclear envelope, rough endoplasmic reticulum, and the Golgi apparatus. The origin of this type of blasts could not be defined by their morphology. Surface marker analysis indicated that most of the leukemic cells expressed platelet markers, gpIIb, gpIIb/IIIa, gpIX, and gpIbalpha. Karyotypic analysis of the bone marrow cells of this unique subset of AMKL demonstrated a novel translocation, t(1;9)(p32;q34).     

流式细胞术CD34+细胞计数在骨髓增生异常综合征分型诊断中的作用

为探讨流式细胞术(FCM)CD34+细胞计数在骨髓增生异常综合征(MDS)分型诊断中的应用价值.采用多参数FCM设门技术检测MDS患者骨髓CD34+细胞计数,与形态学分型诊断比较.结果显示:对照组和MDS组形态学原始细胞计数分别为0.43±0.64%和2.50±3.68%,FCM CD34+细胞计数分别为0.45±0....     

Intrathecal methotrexate-induced megaloblastic anemia in patients with acute leukemia.

OBJECTIVE: To evaluate the occurrence of megaloblastic anemia induced by the infusion of therapeutic or prophylactic methotrexate in patients with acute leukemia. DESIGN: Data on 3 patients with acute leukemia receiving intrathecal methotrexate were prospectively analyzed. SETTING: Large tertiary-care center. RESULTS: All 3 patients with acute leukemia developed megaloblastic anemia confirmed by examination of the bone marrow aspirate and biopsy. Two of the 3 patients had low folic acid levels, while all patients had normal serum B(12) levels. All patients responded favorably to a therapeutic trial of folic acid. The median time for recovery of the hematologic parameters in these patients was 7 days. CONCLUSIONS: Intrathecally administered methotrexate may result in megaloblastic changes in the bone marrow of leukemic patients. The morphologic clues suggestive of folate deficiency in patients with acute leukemia may be masked by coexisting factors, such as the effects of cytotoxic treatment, prior transfusions, or persistent changes from the leukemic clone itself. Caution should be exercised to avoid attributing these changes to the neoplastic process, since the prognosis and treatment for the conditions involved are totally different. Repeat examination of the bone marrow, obtaining folic acid and vitamin B(12) levels, and a therapeutic trial of folic acid may help identify and reverse these changes.