MR imaging features of vaginal malignancies.

Primary vaginal malignancies are rare, accounting for only 1%-2% of all gynecologic malignancies. Squamous cell carcinoma makes up about 85% of primary vaginal malignancies. This tumor characteristically arises from the posterior wall of the upper third of the vagina. The main patterns of disease are an ulcerating or fungating mass or an annular constricting lesion. At magnetic resonance (MR) imaging, squamous cell carcinoma has intermediate signal intensity on T2-weighted images and low signal intensity on T1-weighted images. The tumors that account for the remaining 15% of primary vaginal malignancies are adenocarcinoma, melanoma, and sarcomas. The signal intensity characteristics on MR images correlate with the histologic subtypes and reflect the MR imaging appearances of these histologic subtypes elsewhere in the body. Secondary malignancy of the vagina is far more frequent than primary vaginal malignancy. Most vaginal metastases occur by means of direct local spread from the cervix, uterus, or rectum. The MR imaging appearances of these metastases reflect the MR imaging appearances of the primary tumor.