"Uterine-type" Extra-uterine High-grade Sarcoma of the Rectovaginal Septum: Case Report and Review of Literature.

The rectovaginal septum is an unusual location for neoplastic processes. The majority of these are extensions of tumors of the rectum or vagina. Masses arising primarily from the rectovaginal fascia are rare. Most primary rectovaginal malignant neoplasms are carcinomas that arise in the setting of endometriosis. Sarcomas in this location are exceedingly rare, with only few cases reported in the literature. We report a case of a 44-year-old lady who developed a high-grade sarcoma in the rectovaginal septum in the setting of endometriosis. We also discussed the differential diagnosis of this lady's challenging and unique lesion, which is most probably an extra-uterine "uterine-type" high-grade sarcoma that shows overlapping features of several entities. Moreover, we performed a literature review of sarcomas in this rare location. Given the fact that the rectovaginal septum is a common location for endometriosis, in the case of a rectovaginal neoplasm, a thorough sampling and a careful search for endometriotic lesions are important, as they may be a clue for the diagnosis. Although rare, sarcomas should always be considered in the differential diagnosis of rectovaginal neoplasms.