Well-differentiated papillary mesothelial tumor:a clinicopathological analysis of six cases

ZHANG Ying; DAI Wen-bin; LI Wen-hua; LIANG Yue

doi:10.3969/j.issn.1007-8096.2023.10.006

Abstract：Objective To investigate the clinicopathological characteristics,immunophenotype,diagnosis and differential diagnosis of well-differentiated papillary mesothelial tumor(WDPMT).Methods The clinical and histopathological features of 6 cases of WDPMT were analyzed retrospectively.The expression of CK,Calretinin,CK5/6,WT-1,HBME1,D2-40,Vimentin,ER,PR,PAX-8,TTF-1,NapsinA and Ki-67 was detected by immunohistochemical EnVision two-step method,and the related literature was reviewed.Results Among the 6 patients with WDPMT,2 were male,4 were female,aged 45-73 years(average age 58 years),3 were located in the peritoneum,2 were located in the pleura,and 1 was located in the diaphragm.The tumors were solitary or scattered in miliary or aggregated nodules.Microscopically,the tumors were composed of papillary structures.The papillary stroma was the axis of fiber vessels,and the surface was lined with mild,single-layer flat or cubic epithelioid cells,without obvious atypia.Immunophenotypically,Calretinin,HBME1 and other mesothelial markers were positive,PAX-8 was positive in 1 case(1/6),Vimentin was positive in 1 case(1/6),ER,PR,TTF-1 and NapsinA were negative,and Ki-67 proliferation index<10%.Conclusion Well-differentiated papillary mesothelial tumor is a rare benign or borderline mesothelial tumor,which can survive for a long time after complete resection.It needs to be differentiated from malignant mesothelioma,metastatic adenocarcinoma and serous tumor with similar morphology,so as to improve the understanding of the disease and prevent over treatment.