Distribution of the c-MYC gene product in colorectal neoplasia.

AIMS: Recent attempts to study MYC distribution in human samples have been confounded by a lack of agreement in immunohistochemical staining between antibodies targeting the N-terminus and those targeting the C-terminus of the MYC protein. The aim of this study was to use a novel in-situ hybridization (ISH) approach to detect MYC mRNA in clinically relevant samples, and thereby determine the reliability of MYC-targeting antibodies. METHODS AND RESULTS: We performed immunohistochemistry on human formalin-fixed paraffin embedded normal colon (n = 15), hyperplastic polyp (n = 4) and neoplastic colon samples (n = 55), using the N-terminally directed antibody Y69, and the C-terminally directed antibody 9E10. The MYC protein distributions were then compared with the location of MYC mRNA, determined by ISH. We found that the localization of MYC mRNA correlated well with the protein distribution determined with the N-terminally directed antibody Y69, and was also associated with expression of the proliferation marker Ki67. The protein distribution determined with the C-terminally directed antibody 9E10 was not always associated with MYC mRNA, Y69, or Ki67, and indeed often showed a reciprocal pattern of expression, with staining being strongest in non-proliferating cells. CONCLUSIONS: The observed discrepancy between the staining patterns suggests that the significance of 9E10 in immunohistochemical staining is currently uncertain, and therefore should be interpreted with caution.

Sporadic and endemic Burkitt lymphoma have frequent FOXO1 mutations but distinct hotspots in the AKT recognition motif.

FOXO1 has an oncogenic role in adult germinal center-derived lymphomas, in which mutations, predominately within the AKT recognition motif, cause nuclear retention of FOXO1, resulting in increased cell proliferation. To determine the prevalence and distribution of FOXO1 mutations in pediatric Burkitt lymphoma (BL), we sequenced a large number of sporadic and endemic BL patient samples. We report a high frequency of FOXO1 mutations in both sporadic and endemic BL at diagnosis, occurring in 23/78 (29%) and 48/89 (54%) samples, respectively, as well as 8/16 (50%) cases at relapse. Mutations of T24 were the most common in sporadic BL but were rare in endemic cases, in which mutations of residue S22, also within the AKT recognition motif, were the most frequent. FOXO1 mutations were almost always present in the major tumor cell clone but were not associated with outcome. Analysis of other recurrent mutations reported in BL revealed that FOXO1 mutations were associated with mutations of DDX3X and ARID1A, but not MYC, TCF3/ID3, or members of the phosphatidylinositol 3-kinase signaling pathway. We further show common nuclear retention of the FOXO1 protein, irrespective of mutation status, suggesting alternative unknown mechanisms for maintaining FOXO1 transcriptional activity in BL. CRISPR/Cas9 knockout of FOXO1 in an endemic cell line produced a significant decrease in cell proliferation, supporting an oncogenic role for FOXO1 in endemic BL. Thus, FOXO1 is frequently mutated in both sporadic and endemic BL and may offer a potential therapeutic target for pediatric BL patients worldwide.

Bone marrow trephine morphology and immunohistochemical findings in chronic myelomonocytic leukaemia.

Chronic myelomonocytic leukaemia (CMML) is a clonal disorder with myelodysplastic/myeloproliferative features. Its diagnosis is based on the presence of peripheral blood monocytosis and bone marrow aspirate findings, according to World Health Organization criteria. However, bone marrow trephine biopsy (BMTB) features characteristic of CMML have not been adequately investigated. We studied BMTB in 20 cases of CMML-1 and three cases of CMML-2 and compared with ten cases of polycythaemia vera, ten cases of chronic myeloid leukaemia (chronic phase) and ten cases of florid myeloid hyperplasia (MH). Furthermore, we evaluated the use of CD34, CD117 and CD68 (PGM-1) antibodies in diagnosis and subtyping of CMML and in differentiating from other categories. Hypercellularity, high myeloid:erythroid ratio, increased proportion of 'myelo/monocytic' cells often seen as clusters and/or nodules, absence of eosinophilia, and presence of abnormal localisation of immature precursors (ALIP) and dysmegakaryopoiesis can aid in the diagnosis of CMML in BMTB. CD68 (PGM-1) positive cells amounted to 20.7 +/- 6.1% cells among CMML trephines. The proportion of CD34(+) cells among cases of CMML-1 was /=10% cells in two of three cases and 5% in the other case. Morphological and immunohistochemical features of BMTB samples are extremely helpful in the diagnosis of CMML.

Bone marrow trephine findings in acute myeloid leukaemia with multilineage dysplasia.

Acute myeloid leukaemia (AML) with multilineage dysplasia (MD) is one of the four main categories of AML in the World Health Organization (WHO) classification. The role of bone marrow trephine biopsy (BMTB) histology and immunohistochemistry in the diagnosis of AML-MD is currently unclear. BMTBs were studied in 11 cases of AML-MD and two cases of myelodysplasia that subsequently transformed to AML. Among them, six cases showed trilineage dysplasia and seven showed bilineage dysplasia. With respect to conforming to the WHO definition of AML, documentation of an increased proportion of immature myeloid cells was possible on morphology and counting of immature cells following immunostaining with CD34, CD117 or HLA-DR antibodies. Recognition and quantification of dysplastic features in the haemopoietic lineages was made easier by immunohistochemistry with antibodies to ret40f (glycophorin C), myeloperoxidase, CD61 and/or CD42b, CD34, CD117 and HLA-DR. Based on this relatively small series of cases we show the utility of BMTB and immunohistochemistry as an aid to the diagnosis of AML-MD. This has to be seen not just in light of its utility at diagnosis, but also the role the diagnostic BMTB would play for purposes of comparison when follow-up BMTBs are submitted in this group of patients.

Histopathology of the spleen in T-cell large granular lymphocyte leukemia and T-cell prolymphocytic leukemia: a comparative review.

We review retrospectively the spleen histology in 8 patients with T-cell large granular lymphocyte (LGL) leukemia and 4 with T-cell prolymphocytic leukemia (T-PLL) to identify characteristic patterns of involvement and to distinguish such patterns from those described in other low grade B- and T-cell malignancies. Moderate splenic enlargement with red pulp expansion due to lymphocytic infiltration was characteristic of LGL leukemia. Abnormal lymphocytes expressed cytotoxic granule proteins and were consistently CD45RO and CD5 negative in contrast to normal red pulp T cells. This infiltration respected anatomic boundaries with encroachment but no invasion of white pulp areas. Unlike in hairy cell leukemia, the main differential diagnosis for red pulp lymphocytosis, the white pulp was not only preserved in T-cell LGL leukemia but showed germinal center hyperplasia with expansion of the mantle zones. By comparison, T-PLL spleens showed marked red pulp lymphoid infiltration by medium-sized cells with irregular nuclei and prominent eosinophilic nucleoli. T-PLL lymphocytes, unlike LGLs, were more invasive, infiltrating the spleen capsule as well as white pulp areas. T-cell prolymphocytes did not express cytotoxic granule proteins or NK-cell markers, were CD5+, CD45RO+ like normal spleen T cells, were CD2+, CD3+, CD45+, CD43+, TCRbeta+, but CD25-, CD30-, ALK-1-, TRAP-, DBA44-, and TdT-. Expression of CD4 and CD8 in these cells mirrored that of circulating T-PLL cells. These observations on the morphologic and immunohistochemical appearances of the spleen in T-cell LGL leukemia and T-PLL may aid diagnosis of these uncommon T-cell disorders, particularly T-cell LGL leukemia, where presentation may be cryptic and where unique pathognomonic features, are absent.

ST1571 (imatinib mesylate) reduces bone marrow cellularity and normalizes morphologic features irrespective of cytogenetic response.

The tyrosine kinase inhibitor STI571 (imatinib mesylate, Gleevec) is an effective treatment for chronic myeloid leukemia (CML). We examined bone marrow samples from 53 patients with CML who were receiving STI571 in 3 multicenter phase 2 trials to assess morphologic changes and cytogenetic response to this drug. In most patients with initially increased blasts, the bone marrow blast count rapidly decreased during STI571 therapy. Reductions in cellularity, the myeloid/erythroid ratio (commonly with relative erythroid hyperplasia), and reticulin fibrosis (if present pretreatment) also were seen in most patients, resulting in an appearance resembling normal marrow in many cases. Eighteen patients (34%) had some degree of cytogenetic response. Surprisingly, these striking morphologic changes occurred irrespective of any cytogenetic response to STI571. Thus, STI571 seems to affect the differentiation of CML cells in vivo, causing even extensively Philadelphia chromosome-positive hematopoiesis to exhibitfeatures resembling normal hematopoiesis.

Burkitt's lymphoma: maximising the use of fine needle aspirates by long-term preservation for diagnosis and research.

Fine needle aspirates from Burkitt's lymphoma and other tumours transferred directly into ThinPrep® PreservCyt® (Cytyc UK Ltd, Crawley, UK) buffered alcohol fixative retain their cellular and viral antigens and nucleic acids for many months at ambient temperatures. Despite the presence of blood and debris, cells dried onto slides from droplets and post-fixed in formalin, or sections of paraffin-embedded cell blocks from formalin post-fixed pellets, prove adequate for morphology, immunocytochemistry, in-situ hybridization and molecular biological analyses. Where there is lack of expertise in making thin smears or hospitals lack pathology laboratories and services, PreservCyt® provides an excellent medium for transport elsewhere for diagnosis and research.

In vivo evidence for apoptosis in the bone marrow in systemic lupus erythematosus.

An increase in leucocyte apoptosis and impaired clearance of apoptotic cells has been observed in patients with systemic lupus erythematosus (SLE). Apoptotic cells are likely to be a key source of autoantigens in SLE as they express many of the nuclear autoantigens (in surface blebs and apoptotic bodies) that are relevant to this disease. The clearance of apoptotic cells is usually a rapid process, such that few cells are usually seen in the extracellular environment in vivo. We report a case in which multiple apoptotic bodies were observed in the bone marrow of a patient with SLE that was complicated by an immune-mediated pancytopenia. We have subsequently examined the frequency of apoptotic cells, identified morphologically, and by caspase-3 staining in bone-marrow trephine samples taken from patients with SLE over a 10-year period of follow-up. A high proportion of bone marrows contained apoptotic debris. The novel demonstration of apoptotic bodies in vivo in patients with SLE is unusual and supports the notion that the marrow may be a target organ in the disease. Their abundance is also consistent with the hypothesis that normal clearance mechanisms are defective and/or overwhelmed in SLE.

The expression of minichromosome maintenance protein-2 in normal and abnormal megakaryocytes and comparison with the proliferative marker Ki-67.

The minichromosome maintenance (Mcm) and Cdc6 proteins are important regulators of eucaryotic DNA replication. In most normal tissues, a similar proportion of cells express Mcm-2 and Ki-67. The present study showed that in both normal and abnormal states, the proportion of megakaryocytes expressing Mcm-2 is roughly seven times as many as those that express Ki-67. This is likely to be related to the process of endomitosis and endoreduplication. We also demonstrated that a significantly lower proportion of megakaryocytes in myelodysplastic syndrome express Mcm-2. These findings provide new insights into megakaryocyte biology.

Promiscuous expression of Epstein-Barr virus genes in Burkitt's lymphoma from the central African country Malawi.

Primary BL in Malawian children has a very high frequency association, approaching 100%, with the human herpesvirus EBV. A detailed study carried out on viral gene expression in these tumours, using both fresh material and methanol-fixed FNAs, showed, contrary to prediction, that most belong to a variant "class II" latency category, with lytic cycle-related genes also expressed. That is, in addition to EBNA1 expression, membrane proteins (LMP1/2A), immediate early (BZLF1) and early (IR2 and IR4) genes, a putative viral oncogene (BARF1), CST (BART) antisense transcripts and the viral bcl-2 homologue are expressed in a high proportion of the BLs. Most, but not all, express the small viral (EBER) RNAs. Two other significant observations were made: (i) in addition to expression of cellular cytokine (IL-10) transcripts in all tumours investigated, the normally silent viral IL-10 homologue was expressed in some tumours; (ii) whereas EBNA1 expression from its restricted Qp promoter was generally observed, the nonrestricted Cp/Wp promoter was also active in some tumours. Viral gene expression in the Malawian [endemic (e)] BLs appears to be more promiscuous than predicted from other studies, but expression accords with the cytopathologic picture of eBLs as a rapidly proliferating cell population accompanied by considerable necrosis, and a clinically diverse disease. A small-scale study of relapse Malawian BLs revealed a different picture of viral association, more akin to systemic BL than eBL, where EBV appears to be absent or present only at very low levels. The significance of these findings is considered.