2.7.2\ Malignant Melanoma

Between 1 and 3% of malignant melanomas in women occur in the genital tract, where they typically arise in the vaginal mucosa and infiltrate the uterine cervix. Primary cervical melanoma is rare. Melanomas of the female genital tract are characterized by high signal intensity on T1-weighted images and low signal on T2-weighted images. The degree of signal shortening on T1-weighted images varies with the melanin content. The signal is further altered by intralesional hemorrhage, which is quite common (Moon et al. 1993; Miyagi et al. 1997; Kristiansen et al. 1992).

2.7.3\ Lymphoma

Malignant lymphoma of the cervix is typically due to secondary infiltration by advanced lymphoma from other sites. Primary manifestations in the uterus account for only 2% of all primary extranodal malignant lymphomas and typically affect the cervix. Cervical lymphoma is of low signal intensity on T1-weighted images and of high signal intensity on T2-weighted images and thus resembles cervical squamous cell carcinoma. In most cases, lymphoma can be distinguished from cervical carcinomas by its typically large size and the absence of infiltration of surrounding structures. Another distinctive feature is the avid and diffuse contrast enhancement of primary cervical lymphomas (Dang et al. 1991; Kim et al. 1997).

2.8\ Benign Lesions of the Cervix

2.8.1\ Nabothian Cyst

Nabothian cysts are retention cysts of the cervical glands that develop secondary to chronic cervicitis and are often discovered incidentally. Cervicitis is associated with epithelial proliferation and may lead to localized overgrowth and obstruction of glands. Nabothian cysts usually measure only a few millimeters but may grow in size to over 4 cm and then produce a mass effect. They have an intermediate to higher signal intensity on T1-weighted images that reflects the protein content of the cyst content. On T2-weighted images, they have high signal intensity and are

depicted as round to oval lesions with smooth margins. Their differentiation from the rare adenoma malignum (well-differentiated cervical adenocarcinoma with cystic portions) may be difficult by MRI. The depiction of solid portions surrounding or separating the cysts suggests malignancy (Li et al. 1999).

2.8.2\ Leiomyoma

Fewer than 10% of leiomyomas of the uterus affect the cervix. The typical clinical symptoms of cervical leiomyoma are infertility and complications during pregnancy. The lesions are characterized on T2-weighted images by low signal intensity, smooth contour, and a roundish shape (see Sect. 2.7.2).

2.8.3\ Polyps

Cervical polyps are the most common benign lesions of the cervix. They typically occur in perimenopausal women and often cause bleeding between periods. They are usually pedicled and range in size from a few millimeters to 3 cm. Their pathogenesis is mutifactorial and includes metaplastic processes and inflammatory changes of the cervical glands. Cervical polyps are diagnosed by hysteroscopy. Imaging modalities typically depict them as masses of the endocervix.

2.8.4\ Rare Benign Tumors

The rare benign tumors of the cervix comprise capillary or cavernous hemangioma, lymphangioma, papillary adenofibroma, adenomyoma, fibroadenoma, and mesonephric papilloma.

2.8.5\ Cervicitis

Cervicitis is caused by the same pathogens as vaginitis. These include Trichomonas vaginalis, Candida albicans, and Herpes simplex virus. They invade the epithelium of the portio and cause inflammation of the ectocervix. In contrast, bacteria such as Neisseria gonorrhoeae and

Chlamydia trachomatis affect the cervical glands and cause mucopurulent endocervicitis. Bacterial infection may manifest with vaginal discharge or dull pelvic pain. Occasionally, retention cysts may develop in the cervix and can be demonstrated by MRI but may be difficult to differenti-