Prognostic significance of the presence of epithelial cell clusters in the ascites of patients with pseudomyxoma peritonei

Abstract

Background Pseudomyxoma peritonei (PMP) is a rare condition characterized by intraperitoneal accumulation of mucus due to mucinous neoplasia. The characteristic cytological feature of PMP in the ascites is abundant mucus with or without epithelial cell clusters. However, the prognostic significance of the presence of epithelial cell clusters has not been determined. This study aimed to determine the prognostic significance of epithelial cell clusters in the ascites of patients with PMP. Methods Patients who were clinically and histopathologically diagnosed with PMP and who underwent intraoperative cytological examination of their ascites were included in this study. Cytological characteristics including mucus and epithelial cell clusters, nuclear atypia, and the presence of signet ring cells were investigated. Overall survival was compared based on the presence of epithelial cell clusters or nuclear atypia. Results A total of 283 patients (199 women and 84 men) were investigated. The most common original site was the appendix (244 patients). Ninety patients (31.8%) had mucus without epithelial cell clusters (acellular mucin) while 193 (68.2%) had mucus with such clusters; 134 (69.4%) and 44 (22.8%) of these patients showed low‐grade and high‐grade nuclear features, respectively. Signet ring cells were detected in 15 patients (7.8%). The presence of epithelial cell clusters did not influence overall survival (P = .28); however, high‐grade nuclear features and signet ring cell presence were significant negative prognostic factors (P < .001). Conclusion The presence of high‐grade nuclear features or of signet ring cells should be carefully investigated in the cytological specimens of patients with PMP.