Cytopathologie des tumeurs malignes épithéliales

Epithelial tumours account for 98 % of all malignant breast tumours. The most frequent are common ductal types, lobular and particular types which often have very characteristic cytological aspects. The importance of treatment diagnosis for these particular types can be justified by an often better prognosis. Diagnosing malignancy can be confirmed by a cytological examination. Difficulties occur on the one hand when the atypias are discrete, and on the other hand in confirming the lobular variety of the proliferation. The in situ types can be suggered but it is always impossible to be precise about the cytological in situ or infiltrating character the proliferation. Carcinoma diagnosis in the pre- and post-partum period is often unambiguous ; the difficulty is to know well the physiological changes in the breast during this period so as not to wrongly diagnose malignancy. Carcinomas in man, essentially of the ductal type, can show all the cytological aspects of this tumor. The clinical presentation, in general, suggests malignancy with or without inflammatory cutaneous features, very different from the simple aspect of a gynaecomastia.     

Virus epstein-barr et proliférations lymphoïdes B

EBV driven B-cell lymphoid proliferations occur after the dysfunction of the immune control and they appear in primary or acquired immunodeficiencies. In primary immunodeficiencies, combined variable immune deficiency (CVID), X linked lymphoproliferative disorder (XLP), severe combined immune deficiency (SCID) and Wiskott-Aldrich syndrome (WAS) are frequently associaterd with EBV associated B-cell lymphoproliferative disorders or lymphomas. In acquired immunodeficiency after organ or bone marrow transplantation, the occurrence of lymphoid proliferation is one of the most serious complications. They are B-cell, polymorphic or monomorphic and EBV related in almost all cases in early proliferations after the graft. In HIV infection, EBV associated B-cell lymphoma are mostly observed in profound immunosuppressed patients. They are localised in brain or in other extra nodal sites. They are diffuse large B cell lymphoma having the features of immunoblastic subcategory. HIV related Burkitt lymphoma is associated with EBV in 30 to 70 % of cases. The role of EBV in such lymphoma where oncogenic events are predominant remain to be elucidated as well as in the Burkitt lymphoma occurring in immunocompetent patients (children or adults) where EBV is present in about 15 % of non endemic cases.     

Virus epstein-barr et système immunitaire

Epstein-Barr virus persists in CD27+ resting memory B cells of infected people. In lymph nodes, expression of latency II EBV program allows long term survival of EBV infected B cells. Sometimes a lymphoproliferation occurs due to the expression of latency III program which is associated with viral lytic cycle. This escape is usually controlled by the immune system and leads only to asymptomatic viral excretion in immunocompetent people. The control of EBV infection is mainly achieved with specific cellular immune response. Cytotoxic T CD8 lymphocytes (CTLs) were the first studied and their clinical significance has been demonstrated in transplanted patients in whom they prevent or allow the regression of EBV associated lymphoproliferations.CTLs detect lytic antigens with a high frequency during acute mononucleosis and persist thereafter during the latent infection. CTLs also detect latent antigens, however the frequency and intensity of response are lower in that case. Many epitopes have been described for the EBNA3 group proteins while LMP1, LMP2 a et b and EBNA LP proteins present just a few epitopes and induce moderate responses. EBNA 1 protein escapes to CTLs detection because it is not presented by the major histocompatibility complex class I. EBNA1 seems, however, to induce Th1 TCD4 response. T CD4 lymphocytes (TCD4) detect also EBNA3 proteins. Furthermore TCD4 play another role in EBV cycle, and this through cooperation with B lymphocyte (LB); indeed the CD40ligand of TCD4 interacts with the CD40 of LB.This interaction is necessary to obtain specific TCD4 and TCD8 responses and seems to play a key role in the reactivation of the EBV lytic cycle. Further studies should shed light on the interactions between EBV and TCD4 and determine the respective roles of responses toward latent and lytic antigens. Current data on the EBV specific immune response have already allowed to consider new therapeutic strategies for EBV associated lymphoproliferations by the restoration of cytotoxic responses against one or many epitopes.     

Lésions malpighiennes intra-épithéliales de bas grade et de haut grade: Critères cytologiques et corrélations histopathologiques,Diagnostics différentiels

In 1988, the Bethesda system defined low and high grade squamous intraepithelial neoplasia. This terminology, and the subsequent classifications, is cytology-based and does not deal with the conceptual basis regarding squamous intraepithelial lesions and the subsequent development of cancer.The aim of this system was to standardise diagnostic reporting in cytology and to reduce inter-observer variability as well as to facilitate communication with clinicians, inter-laboratory comparison and statistical analysis.The cytological criteria in common between low and high grade lesions basically consist of nuclear changes (also known as dyskaryosis): increased nuclear size, irregular nuclear shape and contour, hyperchromatism, multinucleation, irregular chromatin distribution, abnormal nucleolar number, size and shape.Low grade squamous intraepithelial lesions include the cellular effects related to human papillomavirus (HPV) infection and cervical intraepithelial neoplasia grade I (CIN I). The cytological changes in this group are mild and are sometimes non-specific. The diagnosis can be uncertain or guarded. Some of these lesions are classified as ASCUS (Atypical Squamous Cells of Undeterined Significance).High grade squamous intraepithelial lesions include cervical intraepithelial neoplasia, grade II (CIN II) and cervical intraepithelial neoplasia grade III/carcinoma in-situ (CIN III). The diagnostic problems posed by these lesions are different from those in low grade lesions: the challenge is to not miss small cells, which can often be few in number but in which the cytological abnormalities are clearly evident.The terms low grade and high grade imply a different diagnosis and a different clinical evolution, but the clinician should be informed that the diagnosis suspected of these lesions should be confirmed by histological studies.     

Quand et comment évaluer la leptinémie?

Leptin seems to play a key role in the maintenance of adipose tissue stocks, coordinating the regulation of eating behavior, metabolic state, energy balance and autonomous nervous system. As a peripheral signal of the nutritional state, it could play a major role in the control of reproductive function from puberty to gestation. Recent data have also shown its participation in angiogenesis, bone formation and immune system function.This review describes the current knowledge of the structure and immuno-chemical characteristics of the leptin molecule, its physio-pathological variations and the analytic tools available to the biologist for its routine practice measurement. The circumstances in which the leptin dosage can provide useful information to the clinician will be defined. The role of leptin evaluation in the better understanding of energy homeostasis regulation will also be discussed.     

Détection et surveillance épidémiologique des résistances bactériennes aux antibiotiques en milieu communautaire

The monitoring of bacterial resistance to antibiotics in non-hospitalized patients is essential. More than 80% of antibiotics are prescribed in the community and many patients can carry multiresistant bacteria after hospitalization. In addition to its role in the diagnosis and assistance in the treatment of the community acquired infections, the biologist can integrate a surveillance network of bacterial resistance to antibiotics. This monitoring must consider historical and medical informations concerning the patients. Previous antibiotic treatment, or hospitalization are factors of major concern in the variation of resistance to antibiotics and species of the bacteria isolated from urinary tract infections in the community.Previous hospitalization is frequently found among patients carrying methicillin resistant Staphylococcus aureus. Recent antibiotic treatment is related to an important prevalence of Streptococcus pneumoniae presenting a decreased susceptibility to penicillin G. The notion of re-infection in often found when Haemophilus influenzae producing β-lactamase are isolated. The monitoring of the evolution of resistance to fluoroquinolones in Neisseria gonorrhoeae, and Salmonella Hadar and the survey of resistance to macrolides in β-haemolytic streptococci are also important objectives.     

Diagnostic des pathologies liées au virus Epstein-Barr

Epstein-Barr virus (EBV), a member of the Herpesviridae familly, infects most human (95 % of the world population). In immunocompetent hosts primary infection results in acute infectious mononucleosis. In immunocompromised hosts, EBV is associated with lymphoproliferative disorders which occur with an incidence 30 to 50 higher than in the immunocompetent host. The laboratory diagnosis of an EBV infection is based on two techniques : demonstration of the virus by viral antigen or viral DNA detection and serologic responses. Direct culture of the virus on B lymphocytes is time consuming and is not of general use.