title: Malignant perivascular epithelioid cell tumor of the retroperitoneum.
abstract: Perivascular epithelioid cell tumors (PEComas) are a rare type of mesenchymal neoplasms characterized by a proliferation of perivascular cells with an epithelioid phenotype and expression of myo-melanocytic markers. The majority of PEComas seem to be benign and usually their prognosis is good. Malignant cases are extremely rare, exhibiting a malignant course with local recurrences and distant metastases. We herein report a case of a malignant PEComa arising in the retroperitoneum. The patient was a 55-year-old woman experiencing abdominal discomfort for approximately one month. Ultrasound and computer tomography (CT) scans of the abdomen revealed a solid mass arising from the retroperitoneum. Microscopically, the tumor was composed of epithelioid cells mixed with spindled cells. The nucleus had significant atypia, and the mitoses were obvious. The focal intravascular tumor embolus was visible. Immunohistochemically, the epithelioid tumor cells were positive for HMB45 and Melan-A, and the spindled tumor celLs were positive for SMA and desmin. Seven months after a surgical resection, an ultrasound revealed liver metastases. In conclusion, the malignant PEComas of the retroperitoneum is a very rare neoplasm with unique morphological and immunohistochemical characteristics. It should be differentiated from other epithelioid cell tumors of the retroperitoneum.
authors.affiliation: Department of Pathology and Experimental Medicine, 306 Hospital of PLA Beijing 100101, China.
authors.forename: Ji-Hua
authors.initials: JH
authors.lastname: Wu
authors.forename: Jin-Lian
authors.initials: JL
authors.lastname: Zhou
authors.forename: Yan
authors.initials: Y
authors.lastname: Cui
authors.forename: Qing-Ping
authors.initials: QP
authors.lastname: Jing
authors.forename: Le
authors.initials: L
authors.lastname: Shang
authors.forename: Jian-Zhong
authors.initials: JZ
authors.lastname: Zhang
mesh_terms: D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary*; D008875:Middle Aged; D054973:Perivascular Epithelioid Cell Neoplasms / Q000556:secondary* / Q000601:surgery; D012186:Retroperitoneal Neoplasms / Q000473:pathology* / Q000601:surgery; D014463:Ultrasonography
keywords: Retroperitoneum; clinicopathology; perivascular epithelioid cell tumors