The utility of flow cytometry in the diagnostic work up of malignant effusions due to nonhematopoietic neoplasms

Abstract

Malignant pleural effusion and peritoneal carcinomatosis are frequent causes of effusion. Cytological evaluation (PAP-stained slides followed by immunocytochemistry, IHC, if applicable) is currently the gold standard for the diagnosis of malignant effusions, but its sensitivity varies between 40 and 80%, being a time-consuming technique. Although flow cytometry (FC) is not routinely used in the diagnosis or follow-up of nonhematopoietic neoplasms, it has the advantage of being rapidly applicable to fresh samples, potentially decreasing the time for the diagnosis. The main objective of this study was to assess the utility of FC as a confirmatory tool in the diagnosis of neoplastic effusions, based on the expression of EpCAM antibody in tumor cells versus the cytological evaluation. In this work 1,535 serous fluids were collected, of which 101 (68 pleural, 33 ascites) were selected through a screening algorithm and sent to the FC and cytological evaluation. Seventy-three of these samples (46 pleural, 27 ascites) were considered malignant as determined by clinical, cytological and radiological criteria. According to our data, 75% (55/73) of these samples were positive by Cytology/IHC and 74% (54/73) by FC. We noticed that, although the sensitivity, specificity, and area under the curve were similar, the turnaround time was shorter when using FC. Moreover, these results clearly improved by combining both techniques. We conclude that FC provides information about malignant effusions faster than immunohistochemical staining, and we believe that performing both techniques in parallel would improve diagnostic performance.

Routine flow cytometry approach for the evaluation of solid tumor neoplasms and immune cells in minimally invasive samples

“…Discordant cases also comprise three samples (one CSF and two pleural) in which MFC identified significant numbers of epithelial cells but the cytological results were falsely negative. One possible explanation for this contradictory data could be related to an inadequate number of cells for cytology (Pillai et al, 2013), artifacts in preparations and the greater number of events analyzed by MFC (Wong‐Arteta et al, 2020). In previous studies, CSF immunophenotype improved sensitivity of classical cytology for diagnosis of leptomeningeal metastases (Milojkovic Kerklaan et al, 2016; Subirá et al, 2012).…”

“…This strategy is similar to previous works by Ferreira‐Facio et al (Ferreira‐Facio et al, 2013) in pediatric patients. In turn, other authors have focused on a particular specimen type such as body effusions (Pillai et al, 2013; Sahu et al, 2021; Wong‐Arteta et al, 2020), FNA(Gautam et al, 2008; Leon et al, 2004), or CSF (Milojkovic Kerklaan et al, 2016; Subirá et al, 2012). Regarding sample selection, specimens for MFC studies were often selected based on a carcinoma history or atypical cytology.…”

“…MFC has a well-established role in the diagnosis, prognosis and follow up of hematolymphoid neoplasms and is successfully performed in peripheral blood, BM, body fluids, and tissue samples (Béné et al, 2016). Out of this context, MFC has been introduced in cancer research (Davidson et al, 2007;Davidson et al, 2012) but few studies are devoted to clinical applications for detection of malignant cells (Acosta et al, 2016;Ferreira-Facio et al, 2013;Ferreira-Facio et al, 2021;Gautam et al, 2008;Wong-Arteta et al, 2020).…”

“…MFC has been used in the past mainly to evaluate DNA ploidy or scatter signals in solid tumors (Davidson et al, 2012). In effusion specimens MFC could be at least as sensitive as conventional cytology (CC) for the detection of abnormal cells (Wong-Arteta et al, 2020). However, it has not been widely adopted, partially due to lack of reproducibility and standardization (Gautam et al, 2008).…”

Issue Highlights – November 2020

“…Hyperactivation of the major signaling pathway PI3K/Akt commonly sustains leukemic cell viability in T-ALL and in the study byBonaccorso, et al, 2020, these investigators learn that PTEN Exon 7 mutated T-ALL cells do not respond to IL7, suggesting other mechanisms support the viability and growth of the tumor cells. What is relevant and exciting to our readership is that the proteomic profile of the pediatric T-ALL cases studied was accomplished by rapid and accurate phosphoflow cytometry rather than classical 'gold standard' western blotting.To assess the utility of flow cytometry in the diagnosis of malignant effusions due to non-hematopoietic neoplasmsWong-Arteta, et al, 2020 studied 101 patient samples [68 pleural effusions, 33 ascites] with markers directed towards CD9, CD45, CD99, CD71, CD56, CD10, CD81, CD200, EPCAM, CD14 and NG2. These researchers learned that when analyzing the results obtained by combining cytology to flow cytometry versus cytology alone, there was an improvement in sensitivity and specificity.…”