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Serous Cavity Fluids: Momentum, Molecules, Markers… And More!
Published 2020 · Medicine
The field of cytopathology successfully implemented standardized reporting with the initial version of the Bethesda System for Reporting Cervical Cytology over 20 years ago and its subsequent updates. Updated terminology reporting systems have also been introduced for cytologic sample reporting in the thyroid, pancreas, urine, salivary gland, and breast as well. As we enter a new decade, the latest effort for improving reporting has gained momentum to incorporate serous fluids in a standardized format. The primary reason to initiate this standardization is the lack of consistency and transportability of current reporting styles in different geographical locations. Cytopathologists still use terms such as “atypical,” “consistent with,” “suggestive of,” and “suspicious for,” which may not convey the true essence of what a cytologic specimen reveals on morphologic examination. The role of serous cavity fluid has also changed, since identifying tumor types and associated targetable proteins for therapy from metastatic disease can be vital to improving patient survival. Serous fluids are rich sources of tumor samples for ancillary tests and can be very helpful for targeted therapy, personalized medicine, biobanking, and research. The proposal to create a system of terminology for serous fluids originated in Porto, Portugal, at the 2018 International Academy of Cytology Tutorial Conference, and resulted in an international collaboration for formalized reporting of serous cavity fluids. There are several goals for this endeavor. First, the proposed terminology should reflect current practices and parallel existing cytology terminology systems. Second, guidelines for practice, such as a definition of an adequate serous sample, should be supported by research studies or, if necessary, expert consensus. Third, the outline of the proposed system should be simple and efficient to allow for accurate correlation between different geographic settings and research endeavors. With these goals in mind, the International System for Reporting Serous Cytopathology was conceived. The proposed terminology for the International System for Reporting Serous Cytopathology includes the categories 1) nondiagnostic, 2) negative for malignancy, 3) atypia of undetermined significance, 4) suspicious for malignancy, and 5) malignant, primary (mesothelioma) or secondary (indicate cell type and possible site of origin). Nondiagnostic specimens are either nonrepresentative for the serous cavity site, such as peripheral blood, or insufficient for interpretation due to cellular degeneration or bacterial overgrowth. Negative for malignancy represents a specimen with nonmalignant cellular components. These elements may represent pathologic disease, but not malignancy itself. The criteria for adequacy to be considered should include sample volume, cellular content, and cellular preservation. The proposed recommendation is that a minimum of 75 mL of serous fluid for cytology be submitted to confirm that a benign fluid is truly benign. Atypia of undetermined significance is a category that is to be used judiciously, as opposed to a wastebasket for suboptimal cases. It is most likely to be used when the number of cellular elements is quantitatively limited but shows nuclear enlargement along with hyperchromasia. There may be particular clinical settings where use of