Diffusely enlarged uterus: evaluation with MR imaging.

Diffuse uterine enlargement is a common clinical finding. Because this abnormality can represent a physiologic manifestation, benign tumor, or malignancy, the diagnostic dilemma of a diffusely enlarged uterus can be challenging. Clinical findings can provide valuable information in regard to physiologic effects, pregnancy-related changes, and hormonal causes. Cytologic examination is essential for identification of cervical and endometrial malignancies. However, since preoperative histologic examination of myometrial lesions is not possible, preoperative distinction between benign and malignant conditions is frequently difficult. Imaging thus plays an important role in evaluation of myometrial lesions. In particular, magnetic resonance (MR) imaging allows specific diagnosis of several different lesions. Signal voids and prominent vessels at MR imaging are characteristic of vascular lesions. Adenomyosis and leiomyomas can be distinguished from other lesions with MR imaging, although a variety of unusual manifestations can be seen. MR imaging findings that allow distinction between leiomyoma and leiomyosarcoma have yet to be clearly established; however, invasion, hemorrhagic necrosis, or rapid growth is suggestive of malignancy. Endometrial stromal sarcoma tends to have distinct MR imaging features that allow differentiation from benign lesions.