Benign Metastasizing Leiomyomas (Bml). An imaging and histological challenge: a case report of pelvic extended localization

Leiomyomas are the most common gynecological tumors; they are benign and originate from smooth muscle cells together with fibrous connective tissue. The most common location is the uterus although rare cases of extra-uterine locations with benign histological features have been described, such as intravenous leiomyomatosis, disseminated peritoneal leiomyomatosis, benign metastasizing leiomyomas, parasitic and retroperitoneal leiomyomatosis, which can present as single or multiple myomatous nodules. These entities must be differentiated from malignant lesions such as leiomyosarcoma. Imaging with different modalities, mainly magnetic resonance imaging, plays an important but not always diriment role in this; histological examination is still necessary for a definitive diagnosis. We describe the case of a 36-year-old woman who eight months after undergoing myomectomy, whose histologic examination was in favor of myoma, underwent an MRI examination at our department as an in-depth diagnostic due to the finding of two inhomogeneous and highly vascularized nodular lesions at the ultrasound checkup performed six months after surgery. Our MR examination was performed using multiplanar T2 weighted sequences with and without fat suppression, T1 weighted fat-suppressed sequences pre and post-gadolinium administration and diffusion weighted imaging and showed the presence of a major myomatous lesion at the level of the isthmus surrounded by many confluent nodules in the pelvis with the same benign features. The MRI findings suggested the diagnosis of benign metastasizing leiomyomatosis, then confirmed by the definitive histological ex- amination which found no malignant features of the lesions.