Fig. 13  Leiomyoma of the anterior vaginal wall. T2WI in (a) sagittal and transverse (b) orientation (vagina with gel) demonstrates a well-circumscribed vaginal mass

(long arrow) of decreased signal intensity (Courtesy Dr. Forstner R, Salzburg, Austria)

bladder or urethra. The commonest location for vaginal leiomyomas is the anterior vaginal wall. Imaging findings resemble those of uterine leiomyomas. Typical leiomyomas appear homogeneous of low T1 and T2 signal (Fig. 13). They may undergo degeneration, with hyaline degeneration demonstrating low T2 signal, myxoid and cystic degeneration showing high T2 signal, and hemorrhagic degeneration demonstrating high signal on both T1WI and T2WI (Walker et al. 2011; Griffin et al. 2010). MRI is particularly useful for distinguishing a vaginal leiomyoma from an “aborting” uterine leiomyoma or other atypical vaginal mass (Walker et al. 2011).

6\ Malignant Neoplasms

of the Vagina and Vulva

6.1\ Vaginal Malignancies

6.1.1\ Primary Vaginal Carcinoma

Primary vaginal carcinoma is rare, accounting for only 2–3% of gynecological malignancies and less than 20% of vaginal neoplasms. It is defined as arising only from the vagina, with no involvement

of the external os superiorly or the vulva inferiorly, the importance of this definition ­correlating with the different approaches in the treatment of cervical and vulval carcinoma.

Squamous cell carcinoma (SCC) accounts for approximately 90% of vaginal malignancies. It is more common in postmenopausal females (median age at presentation, 60 years) and frequently involves the proximal third of the vagina and the posterior wall. Clinically, most women present with painless vaginal bleeding, or less often with abnormal vaginal discharge, urinary tract symptoms, pelvic pain, or a feeling of a mass in the vagina. SCC of the vagina tends to spread early by direct invasion of the bladder and urethra anteriorly and the rectum posteriorly. Approximately, one-third of patients have pelvic or inguinal lymph node metastases at diagnosis.

The precursor for vaginal carcinoma, vaginal intraepithelial neoplasia, and invasive vaginal cancer is strongly associated with human papillomavirus (HPV) infection. Both have similar risk factors as those for cervical carcinoma, including tobacco use, younger age at coitarche, HPV, and multiple sexual partners. Increased incidence of vaginal carcinoma is observed in women with a

Table 1  TNM and FIGO staging for vaginal cancer

previous diagnosis of cervical cancer­ or cervical intraepithelial neoplasia (Walker et al. 2011; Griffin et al. 2010; Gardner et al. 2015; López et al. 2005; Chang et al. 1988; Parikh et al. 2008).

Staging of the disease is primarily based on clinical examination by the International Federation of Gynecology and Obstetrics (FIGO) system (Table 1) (FIGO Committee on Gynecologic Oncology 2009). Pelvic examination continues to be the primary modality for the evaluation of the extent of the disease, although it has limitations, such as the inability to detect metastatic lymphadenopathy and the difficulty to assess local tumor infiltration. Therefore, FIGO encourages the use of cross-sectional imaging, including CT and MRI (FIGO Committee on Gynecologic Oncology 2009). Although CT is recommended for staging, MRI may provide superior evaluation of tumor volume and local extension, both for initial staging and follow-up, to allow for better treatment planning (Walker et al. 2011; Gardner et al. 2015; López et al. 2005; Parikh et al. 2008). Furthermore, MRI may be valuable in depicting pelvic anatomy for surgical and radiation therapy planning.

Primary vaginal carcinoma has a 5-year survival rate of about 80% for stage I or II disease, falling to 20% for stage III or IV disease. Because vaginal carcinoma is rare, treatment planning remains less well defined, often individualized and extrapolated from institutional experience and outcomes in cervical cancer. There is an increasing trend towards organ preservation and treatment strategies based on combined external beam radia-

tion and brachytherapy, often with concurrent chemotherapy, with surgery being reserved for patients with in situ or very early stage disease (American College of Radiology 2013).

6.1.1.1\ MRI Findings

Vaginal carcinoma is best detected on T2WI, as a mass of intermediate to high signal intensity that can be seen as separate from the hypointense vaginal wall. Some neoplasms may contain hyperintense foci, probably representing tumoral necrosis; this finding should raise the possibility of a poorly differentiated component, including adenosquamous carcinoma, mucinous adenocarcinoma, or metastases. The tumor appears isointense on T1WI, and its presence could be suggested in lesions large enough to alter the vaginal contour (Walker et al. 2011; Gardner et al. 2015; Taylor et al. 2007).

Stage I tumors are limited to the vaginal mucosa and appear as a mass expanding and filling the vagina, but with preservation of the low T2 signal of the vaginal wall. In stage II, tumor extension into the paravaginal tissues is well appreciated on MRI by loss of the low T2 signal of the vaginal wall and the presence of abnormal low T1 signal in the paravaginal fat, best detected on axial plane. In stage III, tumor extends laterally to the pelvic sidewall, which is best seen on axial and coronal orientations. On MRI, pelvic sidewall invasion is defined as tumor spread within 3 mm of the internal obturator, levator ani or piriformis muscles, and/or iliac vessels. Increased T2 signal related to edema or direct invasion of the tumor into the musculature may be seen. Tethering of the musculature is also occasionally detected. In stage II and III tumors, coronal T2WI should be performed to evaluate also for possible hydronephrosis. In stage IVA, disease has directly spread beyond the true pelvis and/or invaded the rectum or urinary bladder. Loss of the intervening fat planes and of the normal hypointense T2 signal of the bladder or rectal wall, sometimes associated with contour abnormality such as irregularity and nodularity along the wall are findings suggestive of invasion (Fig. 14). Abnormal enhancement of the bladder or rectal wall and/or direct extension of neoplasm

Fig. 14  FIGO stage IVA squamous cell carcinoma of the vagina. (a) T2WI and (b) post-gadolinium fat-saturated T1WI in sagittal orientation show a large, heterogenous mass replacing the vagina. The tumor appears mainly hyperintense on T2WI, strongly and inhomogeneously enhancing after gadolinium administration. Nonenhancing parts of the mass (asterisk) corresponded to

areas of necrosis on pathology. Loss of the intervening fat planes between the neoplasm and the urethra/rectum suggests invasion. Foley catheter (arrow). (c) T1WI and (d) T2WI in transverse orientation depict vaginal carcinoma (arrow) invading the urinary bladder and the left puborectalis muscle (long arrows) (Courtesy Dr. Forstner R, Salzburg, Austria)

into the bladder or rectum are other signs suggestive of infiltration. Multiple planes are often necessary to verify the presence or absence of neighboring organ invasion. The overall accuracy of MRI in diagnosing bladder and rectal invasion is high, ranging from 96 to 99%. However, MRI may overstage bladder involvement as it is difficult to differentiate peritumoral edema (bullous edema) and inflammation from tumor infiltration; in these cases correlation with cystoscopy is necessary. In stage IVB, disease spreads beyond the pelvis and may involve the peritoneum and small or large bowel loops. The most common sites of

distant metastases are the lung, liver, and bones (Walker et al. 2011; Gardner et al. 2015; López et al. 2005; Parikh et al. 2008).

MRI findings of staging primary vaginal carcinoma are presented in Table 2.

6.1.1.2\ Lymph Node Drainage

Lymph node drainage is important as vaginal carcinoma commonly appears with metastatic lymphadenopathy, even in early stages, with reported rates 6–14% for stage I and 26–32% for stage II disease. The upper third of the vagina drains into the external iliac and para-