Analisi citometrica del liquido peritoneale: esperienza su automazione e microscopia a confronto. Proposta di algoritmo diagnostico

BACKGROUND: Cytometric analysis of liquids can be performed in automation and microscopy. The aim of this work was to highlight when the instrumental and microscopic cellular evaluation of peritoneal fluid could be useful for the diagnosis and therapy.METHODS: The automated analysis was performed on an EDTA test tube sample, using the Body Fluid application of Yumizen 2500 (Horiba, Kyoto, Japan) which counted total leukocytes (BF-WBC), red blood cells (BF-RBC), polymorphonuclear cells (BF-PN) and mononuclear cells (BF-MN). The microscopic analysis was carried out on May-Grünwald Giemsa smears set up and was colored using Yumizen SPS, after centrifugation of the sample at 2000 rpm for 5 minutes.RESULTS: We selected four cases of leukocyte counts on peritoneal fluid. Case 1: 403 leukocytes/μL with 66% PN and 34% MN, under the microscope 52% PN and 48% MN of which 20% lymphocytes, 28% cells with nucleocytoplasmic ratio in favor of cytoplasm, probably of mesothelial origin. Case 2: 1017 leukocytes with 5% PN and 95% MN, under the microscope 3% PN and 97% MN of which 67% lymphocytes, 30% cells surrounded by lymphocytes. Case 3: 4129 leukocytes with 26% PN and 74% MN, under the microscope 1% PN and 99% MN, of which 9% lymphocytes and 90% voluminous mononuclear cells with nucleocytoplasmic ratio in favor of the nucleus, nucleolate, chromatin in large plates and basophilic and vacuolate cytoplasm. Case 4: 69 leukocytes differentiated into PN 4% and MN 96%, differential evaluation was not executable on microscopy due to the scarcity of the elements available.CONCLUSIONS: An algorithm was developed to standardize the diagnostic pathway on the peritoneal fluid: in the case of a cell count <100 we reported only the absolute value of the determined elements; for counts with elements ≥100 we reported the absolute value with the instrumental differentiation in PN and MN expressed in terms of percentage and note relating to the interference on MN of mononuclear elements of probable mesothelial origin; we performed the smear to confirm instrumental data and communicate microscopic evaluation to clinician. Case 4 showed how <100 cellular elements were too few for an effective microscopic evaluation. In our opinion a cut-off of 100 may be the most appropriate number to perform a differential cell evaluation useful to the diagnostic path; however, additional verification is necessary on a more significant number of cases. We also believe that this algorithm can be applied to other fluids except cerebral spinal fluid.