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The authors present two cases of Ewing-like sarcoma of the humerus and femur of a 12-year-old boy and a 28-year-old male, respectively. Identical morphology in both tumors consisted of multiple solid nests with a mosaic collection of small, round, uniform cells with clear cytoplasm and no apparent nuclear atypia. A monotonous structural arrangement, including both rich vascularity of bordering septae and significant admixtures of eosinophil leucocytes, resulted in a final organoid "neuroendocrine-like" pattern. Immunohistochemistry revealed diffuse strong CD10, CD99 and CD138 positivity. Detailed molecular analysis in both tumors confirmed translocation t(20;22) resulting in an EWSR1-NFATc2 fusion gene. Additionally, this translocation was accompanied by amplification of the proximal part of the genes and surrounding areas. Clinically, both neoplasms behaved aggressively and they were primarily chemoresistant. Four years later, the patient with the lesion in the humerus developed a massive local recurrence with a disruption of osteosynthesis. The last follow-up disclosed suspicious metastatic deposits in the lung. The boy with the femoral tumor underwent a total femoral prosthesis and there are no signs of local or systemic recurrence after 11 months of follow-up. The authors discuss the taxonomic placement of these rare examples of Ewing-like sarcoma family in the light of new molecular discoveries.

I-FISH (fluorescence in situ hybridization on interphasic nuclei) represents a laboratory method linking morphological investigations (histological sections of formaldehyde fixed and paraffin embedded tissues) with molecular techniques (sequence specificity of nucleic acids bases for a certain locus). I-FISH is relatively undemanding for a laboratory workout, but offering a lot of important information about the investigated cells. Within a scope of pathology departments I-FISH is utilized mostly in diagnostics of neoplasms. I-FISH is helpful in detecting gene copy numbers (amplifications or deletions), and, importantly, in establishing copy numbers of individual chromosomes (polysomies or monosomies), chromosomal breaks and translocations. At present, I-FISH is used not only for diagnosis and estimation of prognosis, but also as a method to qualify a patient for a targeted biological therapy. Because demands on investigation of solid tumors keep raising I-FISH becomes a part of routine investigations. The aim of this paper is to summarize principles and the utility of I-FISH and to help the interested readers in finding a basic orientation in this laboratory method.

Objective: Information on preimplantation diagnostics (PGD) by means of the method of fluorescent in situ hybridization (FISH) and some factors, which principally influence the results obtained with this technique from the point of view of a molecular cytogeneticist. Critical steps of work with one cell in PGD-FISH are summarized based on data from literature as well as from the authors, own experimental experience. The individual steps are analyzed and possibilities of execution are presented., Type of Study: A review., Setting: Institute of Medical Genetics and Fetal Medicine of Faculty Hospital and Medical Faculty of Palacky University, Center of Assisted Reproduction at Obstetric-Gynecological Clinic, Faculty Hospital, Olomouc. SUBJECT AND METHODS OF STUDY: Introduction into the PGD problem. A survey and analysis of factors decisive for the success of the FISH method for PGD. - Selection of embrya for the experimental phase of PGD-FISH. - Selection of fixation method and pretreatment, application of suitable probes. - Localization of the fixed cell. - Interpretation of the results obtained. Recommendation of the mode of their successful solution., Conclusion: The paper presents a survey of the PGD-FISH method. Some critical aspects in the analysis of unicellular preparation are pointed out and evaluated and possibilities and procedures of the optimal solution are suggested.

Objective: Presentation of preimplantation genetic diagnosis and the set of laboratory processes like aspiration, preparation and evaluation of polar bodies, sperm cells and blastomeres using FISH method (fluorescent in situ hybridization) in ART., Design: Review., Setting: Sanatorium REPROMEDA, Brno, Veterinary Research Institute, Brno., Methods: Overview of published data and own clinical experience with the cell aspiration methods, evaluated sample preparation and the proper chromosomes visualisation using FISH method., Conclusion: The review brings an overview of conditions and methods including sample obtaining, FISH analysis preparation and implementation, processed during PGD.

Various techniques are now available for wide genome screening of alterations in copy number, structure and expression of genes and DNA sequences. Molecular cytogenetics has special techniques of comparative genomic hybridization (CGH), spectral karyotyping (SKY) and multicolor FISH (mFISH). We present principles of these methods, their use in molecular cytogenetic examinations of patients. We quote our experience with mFISH for analyses of complex chromosomal rearrangements in neoplastic cells and identification of inborn supernumerary marker chromosome. Further, we also review the first experiences with multicolor high resolution banding of chromosome (mBAND). This method was used for analysis of bone marrow cells of patient with myelodysplastic syndrome and deletion of chromosome No. 5. With mBAND exact breakpoints were localized. Multicolor fluorescence methods mFISH and mBAND becones the new tools for more precise analyses of inborn and acquired numerical and structural chromosomal rearrangements.

During the last few years molecular biology methods expanded into human cytogenetics. This is in close connection with advanced technologies of DNA probes preparation and possibilities of their non-radioactive labelling by means of enzymatic incorporation of modified nucleotides as well as their hybridization with complementary DNA of chromosomes and interphase nuclei. FISH became a useful method in the clinical research. We present the short review of FISH methodologies and their applications for studies of translocation, deletions, amplifications and other chromosomal rearrangements in genetic and oncologic patients. The sensitivity of these methods is approximately 1-10 kb and therefore precise localization of genes on chromosomes is possible. Except gene mapping FISH can be used for comparative genomic mapping (CGH) and for identification of chromosomal changes of tumor cells.