Molecular and Immunohistochemical Characteristics of Primary Vaginal Leiomyosarcoma: Case Report and Review of the Literature

Primary vaginal leiomyosarcoma is a rare malignancy characterized by similar histologic features as uterine leiomyosarcomas. Previous studies of uterine leiomyosarcomas have shown specific molecular alterations, including frequent alterations in TP53, RB1, ATRX, PTEN, MED12, CDKN2A , and MDM2 . Similar alterations have been found in primary vaginal leiomyosarcomas as well as an alternative tumorigenic pathway associated with HPV. Herein, we describe a primary vaginal leiomyosarcoma in a 46-yr-old patient. The tumor was located in the vaginal wall without involvement of the uterus or cervix. Morphologically, it was composed of atypical, spindled cells, with a mitotic rate of 25 mitotic figures per 10 high-power fields and tumor type necrosis. Immunohistochemistry showed positivity for h-caldesmon, SMA, desmin, and ER, along with p53 null pattern expression and loss of ATRX and Rb. Next-generation sequencing analysis revealed mutations in ATRX and PTEN , along with homozygous deletions of RB1 , and deep deletions in TP53 and NCOR1 tumor suppressor genes. High-risk human papillomavirus (HR-HPV) E6/E7 mRNA in situ hybridization was performed and showed no staining.