A Case Study of a High-Grade Serous Carcinoma of the Fallopian Tube Transformed into Carcinosarcoma at the Site of Peritoneal Dissemination With Immunohistological Evidence of an Epithelial–Mesenchymal Transition

We report a patient in whom a primary high-grade serous carcinoma (HGSC) of the fallopian tube transformed into a carcinosarcoma at the site of peritoneal dissemination, and immunohistological analysis suggested the involvement of an epithelial-mesenchymal transition (EMT). The patient, a 70-year-old woman, had an abdominal mass palpated on admission, and a laparotomy was performed after a close examination. The resected right fallopian tube was cystically dilated, and a solid mass was observed in its lumen. The histological diagnosis was HGSC of the right fallopian tube with a papillary or complex tubular structure composed of tumor cells with marked nuclear irregularities. p53 was overexpressed, and no mesenchymal tumor component was observed. The resected left-sided abdominal mass of the omentum was a solid with a long diameter of 100 mm. Microscopically, the tumor exhibited a mixture of HGSC and high-grade sarcoma with nonspecific differentiation. Furthermore, a heterologous chondrosarcoma was subsequently observed from the high-grade sarcoma. The HGSC component was E-cadherin positive. The high-grade sarcoma component was positive for EMT-related proteins such as zinc finger E-box-binding homeobox 1 (ZEB1) and twist family bHLH transcription factor 1 (TWIST1). The chondrosarcoma component was ZEB1 positive and TWIST1 negative. p53 overexpression was found in all 3 components. The tumor of the omentum suggested that an EMT phenomenon was involved in the tumorigenesis. In this scenario, the primary HGSC of the fallopian tube with obvious invasion demonstrated that the conversion from carcinoma to sarcoma by EMT occurs only with peritoneal dissemination.