Juvenile chronic myeloid leukemia. A malignancy of S-100 protein-positive histiocytes

Mice expressing KrasG12D in hematopoietic multipotent progenitor cells develop neonatal myeloid leukemia

Juvenile myelomonocytic leukemia (JMML) is a pediatric myeloproliferative neoplasm that bears distinct characteristics associated with abnormal fetal development. JMML has been extensively modeled in mice expressing the oncogenic KrasG12D mutation. However, these models have struggled to recapitulate the defining features of JMML due to in utero lethality, nonhematopoietic expression, and the pervasive emergence of T cell acute lymphoblastic leukemia. Here, we have developed a model of JMML using mice that express KrasG12D in multipotent progenitor cells (Flt3Cre+ KrasG12D mice). These mice express KrasG12D in utero, are born at normal Mendelian ratios, develop hepatosplenomegaly, anemia, and thrombocytopenia, and succumb to a rapidly progressing and fully penetrant neonatal myeloid disease. Mutant mice have altered hematopoietic stem and progenitor cell populations in the BM and spleen that are hypersensitive to granulocyte macrophage-CSF due to hyperactive RAS/ERK signaling. Biased differentiation in these progenitors results in an expansion of neutrophils and DCs and a concomitant decrease in T lymphocytes. Flt3Cre+ KrasG12D fetal liver hematopoietic progenitors give rise to a myeloid disease upon transplantation. In summary, we describe a KrasG12D mouse model that reproducibly develops JMML-like disease. This model will prove useful for preclinical drug studies and for elucidating the developmental origins of pediatric neoplasms.

Protein signatures as potential surrogate biomarkers for stratification and prediction of treatment response in chronic myeloid leukemia patients

There is unmet need for prediction of treatment response for chronic myeloid leukemia (CML) patients. The present study aims to identify disease-specific/disease-associated protein biomarkers detectable in bone marrow and peripheral blood for objective prediction of individual’s best treatment options and prognostic monitoring of CML patients. Bone marrow plasma (BMP) and peripheral blood plasma (PBP) samples from newly-diagnosed chronic-phase CML patients were subjected to expression-proteomics using quantitative two-dimensional gel electrophoresis (2-DE) and label-free liquid chromatography tandem mass spectrometry (LC-MS/MS). Analysis of 2-DE protein fingerprints preceding therapy commencement accurately predicts 13 individuals that achieved major molecular response (MMR) at 6 months from 12 subjects without MMR (No-MMR). Results were independently validated using LC-MS/MS analysis of BMP and PBP from patients that have more than 24 months followed-up. One hundred and sixty-four and 138 proteins with significant differential expression profiles were identified from PBP and BMP, respectively and only 54 proteins overlap between the two datasets. The protein panels also discriminates accurately patients that stay on imatinib treatment from patients ultimately needing alternative treatment. Among the identified proteins are TYRO3, a member of TAM family of receptor tyrosine kinases (RTKs), the S100A8, and MYC and all of which have been implicated in CML. Our findings indicate analyses of a panel of protein signatures is capable of objective prediction of molecular response and therapy choice for CML patients at diagnosis as ‘personalized-medicine-model’.

Skin Infiltration of Juvenile Myelomonocytic Leukemia

We described a two-year-old boy who developed a skin infiltration from JMML. Several indurated erythematous lesions were seen on his back on his first visit to our department. Edematous erythemas had repeatedly appeared on his auricles and feet for the previous six months. He had had a high fever for a month. Hepatosplenomegaly and superficial lymphadenopathy were recognized. Laboratory investigation showed leukocytosis and anemia. The diagnosis of JMML was confirmed by the findings of myeloid hyperplasia in his bone marrow and the spontaneous colony formation and GM-CSF hypersensitivity in a culture of bone marrow cells. Histopathologically, large atypical mononuclear cells were infiltrated throughout the dermis in a perivascular and interstitial distribution in a skin biopsy specimen. These cells were CD3 (-), CD20 (-), CD45 (+), CD68 (+) and myeloperoxidase (+). Bone marrow transplantation and then cord blood stem cell transplantation were performed but soon rejected. The indurated erythematous lesions appeared again soon after the relapse of JMML. There are other reported cases of JMML with skin infiltration that preceded any other manifestations of the disease. JMML cells in some patients, including our case, seem to have a great affinity for the skin, and skin biopsy aids in early detection of this disease.

Histologic findings in skin biopsy in a JMML rash: a case report and review of literature

Juvenile myelomonocytic leukemia (JMML), belonging to the category of myeloproliferative/myelodysplastic syndromes, is a rare pediatric hematologic malignancy with frequent skin manifestations commonly in the form of rashes. However, these rashes are not always biopsied and their immunophenotype studied in details. We report one such case in a 2-year-old boy who presented with a 1-month history of nonresolving fever, fatigue, and pallor along with a generalized maculopapular skin rash. The child also had mild hepatomegaly. A complete blood count with differential revealed a hemoglobin value of 8.6 g/L, leukocytosis (white blood cell count of 55.3 × 109/L), absolute monocytosis (27 × 109/L), immature granulocytes, and a platelet count of 126 × 109/L. The bone marrow aspirate showed a hypercellular marrow with trilineage hematopoiesis, 10% blasts (including promonocytes), increased monocytes (46%), and dysplastic changes in the erythroid and myeloid cell lines. These findings along with absence of a BCR-ABL1 fusion gene and a hemoglobin F level of 3.4% were consistent with the diagnosis of JMML, which was confirmed by subsequent positive granulocyte macrophage-colony stimulating factor hypersensitivity and NRAS mutation studies. A skin biopsy of the rash revealed a dermal infiltrate composed predominantly of atypical monocytic cells that were positive for CD68, myeloperoxidase, and lysozyme and negative for CD117, CD1a, and S100, consistent with JMML.

Differentially expressed cytosolic proteins in human leukemia and lymphoma cell lines correlate with lineages and functions

Identification of cytosolic proteins differentially expressed between types of leukemia and lymphoma may provide a molecular basis for classification and understanding their cellular properties. Two-dimensional fluorescence difference gel electrophoresis (DIGE) and mass spectrometry have been used to identify proteins that are differentially expressed in cytosolic extracts from four human leukemia and lymphoma cell lines: HL-60 (acute promyelocytic leukemia), MEC1 (B-cell chronic lymphocytic leukemia), CCRF-CEM (T-cell acute lymphoblastic leukemia) and Raji (B-cell Burkitt's lymphoma). A total of 247 differentially expressed proteins were identified between the four cell lines. Analysis of the data by principal component analysis identified 22 protein spots (17 different protein species) differentially expressed at more than a 95% variance level between these cell lines. Several of these proteins were differentially expressed in only one cell line: HL-60 (myeloperoxidase, phosphoprotein 32 family member A, ras related protein Rab-11B, protein disulfide-isomerase, ran-specific GTPase-activating protein, nucleophosmin and S-100 calcium binding protein A4), and Raji (ezrin). Several of these proteins were differentially expressed in two cell lines: Raji and MEC1 (C-1-tetrahydrofolate synthase, elongation factor 2, alpha- and beta-tubulin, transgelin-2 and stathmin). MEC1 and CCRF-CEM (gamma-enolase), HL-60 and CCRF-CEM (ubiquitin-conjugating enzyme E2 N). The differentially expressed proteins identified in these four cell lines correlate with cellular properties and provide insights into the molecular basis of these malignancies.

Juvenile chronic myelocytic leukemia--report of 10 cases

Ten children (five boys and five girls) with juvenile chronic myelocytic leukemia were seen over a period of 12 years (1980-1991) at the All India Institute of Medical Sciences, New Delhi. With the exception of one who was aged 4.5 years, all children were below 4 years of age (mean age 20.4 months). The presenting features included fever, bleeding secondary to thrombocytopenia, marked hepatosplenomegaly, and skin rash. The striking hematological features were anemia, thrombocytopenia, peripheral blood monocytosis, and normoblastemia. There was no significant myeloid proliferation in the bone marrow aspirate (mean M:E = 5:1), while erythroid proliferation was prominent along with monocytosis (mean 11.2%). Fetal hemoglobin was raised in 8 of the 10 patients (mean 14.1%). Long-term survival was poor, with maximum survival being 18 months in one case. New modalities of management of this rare entity are discussed.

Clinicopathologic study of large cell anaplastic lymphoma (Ki-1-positive large cell lymphoma) among the Japanese

The clinical, prognostic, phenotypic, and genotypic findings of 30 patients with large cell anaplastic lymphoma (Ki-1-positive large cell lymphoma) were analyzed. There were 13 male and 17 female patients (male-female ratio, 0.8) whose ages ranged from 3 to 81 years of age (mean, 28 years of age; 67% of the patients younger than 30 years of age). The 5-year survival rate was 52%; this was better than that of other types of high-grade peripheral T-cell lymphoma. Histologic examination showed distinctive morphologic features such as tumor cell pleomorphism, sinus infiltration, fibrosis, partial lymph node involvement, sparing of B-cell regions, and occasional plasma cell infiltrates. Eighty percent of the cases were of T-cell phenotype, and others expressed neither B-cell nor T-cell markers. The tumors were frequently positive for a histocompatibility antigen (HLA-DR), CD25 (the interleukin-2 receptor), and epithelial membrane antigen. Rearrangements of the T-cell receptor beta gene were observed in nine of 13 cases (69%). These findings indicated that many of the tumors had the phenotype and genotype of activated T-cells. This study also showed that large cell anaplastic lymphoma has a survival figure intermediate between Hodgkin's disease and low-grade peripheral T-cell lymphoma.

Acute myeloid leukemia: immunohistologic findings in paraffin-embedded bone marrow biopsy specimens

Immunohistochemical investigations were performed on decalcified, paraffin-embedded iliac crest trephine biopsy specimens from 30 cases of acute myeloid leukemia (AML, as defined by the FAB classification) with antibodies against B cells (L26, 4KB5, MB1, Ki-B3), T cells (UCHL1, MT1), myeloid/histiocytic cells (anti-neutrophil elastase, MAC387, anti-S-100 protein, anti-alpha 1-antichymotrypsin, DAKO-M1), natural killer/killer cells (anti-Leu-7), and megakaryocytes (anti-factor VIII-related antigen). (1) The blast cells of all the cases reacted with from at least two to at most eight different antibodies. Each antibody reacted with blast cells in a minimum of two (maximum 30) cases. (2) MT1, Ki-B3, anti-alpha 1-antichymotrypsin anti-neutrophil elastase, anti-S-100 protein, and MAC387 stained blast cells in more than 50% of the cases; MB1, L26, UCHL1, 4KB5, and DAKO-M1 in 20% to 50% of the cases; and anti-Leu-7 and anti-factor VIII-related antigen in less than 20% of the cases. (3) In the majority of cases many T lymphocytes, a small-to-moderate number of B lymphocytes, and a few Leu-7-positive lymphoid cells were intermingled with the blast cells. In some cases, especially where only a minor proportion of the blast cells was immunostained, it was nearly impossible to distinguish the lymphocytes of the tumor's stromal reaction from small blast cells. Thus, AML exhibits a heterogeneous immunophenotype in trephine biopsy specimens. Immunohistologic diagnosis of this disease in such specimens may be extremely difficult. Since staining of the blast cells with one or more of the antibodies generally used to define B cells, T cells, or their neoplastic derivatives is not uncommon, misinterpretation as non-Hodgkin's lymphoma of high-grade malignancy could easily occur. These findings also suggest that mixed-type (hybrid) acute leukemias with coexpression of myeloid and lymphoid cell markers could be more common than generally realized.