Published online Sep 26, 2020. doi: 10.12998/wjcc.v8.i18.4207
Peer-review started: April 14, 2020
First decision: July 25, 2020
Revised: July 30, 2020
Accepted: August 25, 2020
Article in press: August 25, 2020
Published online: September 26, 2020
Processing time: 160 Days and 19.9 Hours
Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal tumor that exhibits an epithelioid and spindle cell morphology. The tumor is characterized by immunoreactivity for melanocytic and myogenic markers but can be misdiagnosed as more common tumors with similar characteristics, including gastrointestinal stroma tumors or leiomyosarcomas. Recently, a subset of PEComas has been reported to harbor a transcription factor binding to TFE3 fusion. Herein, we report a rare case of TFE3-expressing malignant PEComa arising from the mesentery.
A 50-year-old woman presented with abdominal discomfort for 3 months. Results of laboratory tests were all within the normal ranges, and the patient had no notable medical history. Magnetic resonance imaging revealed a large tumor on the right side of the pelvic floor, which was originally suspected to be a primary ovarian tumor. However, during surgery, the tumor was revealed to have originated from the mesentery. Histologically, the tumor was composed of bundles of spindle cells and sheets of epithelioid cells. Extensive coagulative necrosis and numerous mitotic figures were observed. Immunohistochemistry revealed that the tumor cells were positive for smooth muscle actin, HMB-45, and TFE3 expression. Tumor involvement of the rectal serosa was identified, leading to a final diagnosis of malignant PEComa of the mesentery. Surgical resection was followed by adjuvant chemotherapy. No recurrence or metastasis was observed over a 6-month follow-up period.
Malignant PEComa of the mesentery is extremely rare and should be distinguished from morphological mimics through differential diagnosis and immunohistochemistry.
Core Tip: Primary mesenchymal tumors originating from the mesentery are rare and can only be diagnosed histologically. Broad differential diagnoses and immunohistochemical analyses are required along with consideration of perivascular epithelioid cell tumor among differential diagnoses.