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Background Even in experienced hands, the classification of some melanocytic lesions of the conjunctiva remains challenging. In skin pathology, the recent application of fluorescence in situ hybridisation (FISH) has been demonstrated to be of use for the analysis and diagnosis of ambiguous melanocytic neoplasms of the skin. This study set out to evaluate this method on seven prospective conjunctival cases that were histologically equivocal. Methods 18 unequivocal retrospective melanocytic controls were exposed to FISH. Commercially available probes assessing copy numbers of RREB1 (6p25), MYB (6q23) and CCND1 (11q13) genes compared with CEP6 (a chromosome six centromeric reference point) were used. After control verification, seven prospective, equivocal cases were identified and exposed to FISH. Results There was complete correlation between FISH result and the control section histopathology report. Control cases of melanoma cases were all positive for FISH and control benign lesions were negative. Of the seven equivocal cases, five were positive and classed as invasive melanoma or melanoma-in situ, one was negative and one tetraploid, classed as negative (these last two cases were classed as naevi with careful clinical observation). Conclusions FISH is very useful in classifying equivocal conjunctival melanocytic lesions, especially those with atypical junctional activity and naevoid melanocytic proliferations of the conjunctiva. [ABSTRACT FROM AUTHOR]

Multiple Myeloma (MM) is a neoplastic proliferation of bone marrow plasma cells. Plasma cells, even in MM, can be present in relatively low numbers and divide infrequently. Consequently, conventional metaphase cytogenetic studies can be extremely difficult. Chromosome abnormalities are reported in 18-36% of newly diagnosed MM. This figure is very low when compared to 60-80% with abnormal DNA content as shown by flow cytometry and even higher levels of abnormality suggested by recent in situ hybridisation reports. Standard Fluorescence in situ Hybridisation (FISH) techniques do not discriminate between normal cells and plasma cells, and as abnormalities can be present in only a proportion of the plasma cells, detection of the abnormal clone can be problematic. We present a robust technique for detecting plasma cell abnormalities by immuno-FISH suitable for use in a diagnostic laboratory. The technique involves separation of white cells and preparation of cytospin slides. Plasma cells are then identified by using FITC-conjugated antiantibodies (DAKO) directed against human Kappa and Lambda light chains. This is carried out prior to performing standard in situ hybridisation techniques. Analysis can then be targeted to plasma cells only. We demonstrate the use of the Vysis SpectrumOrange Rb1 probe for 13q deletion detection, but the technique could be extended to dual colour probes such as the Vysis IgH breakapart probe. [ABSTRACT FROM AUTHOR]