Objective: To investigate the clinicopathological characteristics and differential diagnosis of primary peritoneal adenocarcinoma.
Methods: The clinico-pathological data of 8 patients with primary peritoneal adenocarcinoma, all female, aged 55.7 (45 - 69), were analyzed retrospectively. Immunohistochemistry was used to detect the expression of pan-cytokine, cytokine (CK) 7, CK20, CA125, CEA, epithelial membrane antigen (EMA), vimentin, calretinin, and P63 in the specimens of tumor obtained during tumor reduction surgery. Microscopy was conducted for pathological examination.
Results: The common clinical symptoms of these 8 patients included abdominal distention and ascites. Pre-operationally, 6 cases were diagnosed as with ovarian cancer, I case as with malignant mesothelioma, and I as with peritoneal carcinoma. The misdiagnosis rate was 87.5%. Post-operational pathological examination showed 7 cases of serous papillary adenocarcinoma and one case of mucinous adenocarcinoma. Immunohistochemistry showed the positive rates of the different biological markers as follows: pan-CK (8/8), CK7 (8/8), CK20 (1/8), CA125 (7/8), CEA (7/8), EMA (8/8), vimentin (1/8), calretinin (1/8), and P53 (8/8).
Conclusion: A rare malignant tumor arising from the secondary Müllerian system, primary peritoneal adenocarcinoma shares similar histopathological characters with ovary carcinoma, so is easy to be misdiagnosed. Immunohistochemical staining is helpful to the differential diagnosis.