An Extremely Rare Epithelioid Sarcoma Arising from the Infratemporal Fossa: A Case Report and Literature Review

Introduction: Epithelioid sarcoma (ES) is a rare histopathological type of soft tissue sarcoma. They are subcutaneous soft tissue masses that tend to arise in extremity sites (the classic type, formerly referred to as distal type) or proximal midline region of the body (the proximal type), such as the perineum, genital tract, and pelvis. The head and neck regions are rarely affected by ES, but the infratemporal fossa (ITF) is extremely rare. ES involving the ITF has not been reported before in literature. In this paper, the imaging features of ES were reviewed in detail, and the anatomical structure and epidemiology of ITF were briefly introduced. Sources: We performed a systematic search from 3 databases, CNKI(China National Knowledge Internet), FMRS(Foreign Medical Literature Retrieval Service, Shenzhen METSTR Technology CO., Led. China), and PubMed, to obtain literature from January 1970 to July 2020. Epithelioid sarcoma, head and neck regions, infratemporal fossa, diagnostic imaging, anatomy, MRI, and CT were used as keywords for advanced retrieval. A study had to be found eligible for inclusion to be closely related to ES and/or ITF. A total of 129 related pieces of literature were retrieved successfully, of which 37 were closely related to this study. The case report in this article is from the Affiliated Hospital of North Sichuan Medical College. The present study was approved by the institutional review board of the Affiliated Hospital of North Sichuan Medical College and a written informed consent for the publication of the case was obtained from the patient. Case Presentation: A 33-year-old man accidentally found a slowly growing, painless mass in the left cheek more than a month ago. On plain computed tomography (CT) scan of the outpatient department, an oval slightly low-density mass with well-defined and uniform boundary in the infratemporal fossa was revealed, and on the contrast-enhanced scan, it was homogeneous and moderately enhanced. Initially, the CT appearance favored benign lesions. However, the possibility of a malignant tumor can not be excluded completely. Finally, the patient was referred to the inpatient department a tumor arose from IF and underwent a selective operation. The tumor was completely removed. Histologic findings were compatible with epithelioid sarcoma. Post-operatively, the patient received 2 cycles of radiotherapy, and there was no evidence of recurrence after 6 months follow- up. Conclusion: The imaging manifestations of ES are various. The anatomic structure of ITF is complex and the pathological types are various. It should be very careful in the qualitative diagnosis of tumors from the ITF, and advanced imaging techniques will be useful in imaging diagnosis.