[Serous fluid cytopathology : International system: Ancillary studies for serous fluids and special considerations for peritoneal washings]

The International System for serous fluids cytopathology is a cytologic classification which purpose is to establish a consensus on diagnostic terminology. The exponential discovery of prognostic and theranostic molecular alterations in many cancers, particularly in advanced stages, led the authors to describe the indications and the feasibility of these new markers on cytological samples from serous effusions. The various immunocytochemistry techniques, FISH and those testing DNA and RNA are reported in regard to their ability to identify the main targets currently explored in routine practice. The vast majority of these crucial markers can be reliably tested on effusion fluids. The International System for serous effusion fluids also includes a chapter dedicated to peritoneal washings and the application of the classification to this particular type of sample. The objective is to "wash" the peritoneal cavity with a saline solution to unfix cells from the cavity's wall and collect those that have previously naturally detached. This procedure, performed before surgery of tumors and before any manipulation, allows a cytological analysis that specifies the staging of gynecological and non-gynecological tumors and excludes occult malignant cells in the presence of tumors appearing benign.

[Serous fluid cytopathology: International system]

The International System for Serous Fluid Cytopathology is a cytologic classification which purpose is to establish a consensus on diagnostic terminology. Five diagnostic categories are proposed associated to an increased rate of malignancy and specific cytological criteria. The categories are reported as: (I) Non-diagnostic (ND), the cells are insufficient for interpretation; (II) Negative for malignancy (NFM), only benign cells are present; (III) Atypia of undetermined significance (AUS), the cells present mild atypia more likely to be benign, but a malignant process cannot be definitively excluded; (IV) Suspicious for malignancy (SFM), the cells are present with atypia or in a number suspect of malignancy but with insufficient ancillary studies to give a positive malignant diagnosis; (V) Malignant (MAL), the cytological criteria are absolutely and definitively malignant. Malignant neoplasia can be primitive, it involves mesothelioma and serous lymphoma but most are secondary and correspond mainly to adenocarcinomas in adults and leukemia/lymphoma in children. The diagnostic should always be provided in the appropriate clinical context and be as definitive as possible. The ND, AUS and SFM are temporary or last intention categories. Immunocytochemistry in association with FISH or flow cytometry allow in most cases a conclusive diagnosis. These ancillary studies as well as ADN and ARN tests on effusion's fluids are particularly suited to give reliable theranostic results for personalized therapies.