What are MRI findings of Spine Benign Metastasizing Leiomyoma? Case report with literature review

Introduction: Benign Metastasizing Leiomyoma (BML) is a rare disease that results from metastasis of uterine leiomyoma to distant sites with benign pathologic features. Spine BML is very rare so the information of its features and pathophysiology is seldom known. Materials and Methods: We experienced a case of 42-year-old woman who presented with right buttock and leg pain with paresthesia. She had a surgical history of uterine myomectomy. Magnetic resonance imaging (MRI) of the lumbar spine revealed a well-circumscribed mass lesion in the posterior compartment of the L4 vertebral body, with extension into the ventral epidural space and both foramina. The mass showed hypointensity on T1-, T2-weighted images and strong homogeneous enhancement on gadolinium enhanced T1-weighted images. Tumor removal was conducted, and permanent biopsy revealed the mass as leiomyoma. Nine previous spine BML reports, which are known for all, were reviewed along with our case. We collated the clinical information and MRI findings of spine BML to figure out its common denominators. Results: Premenopausal women, previous history of uterine myoma, myomectomy/hysterectomy, and lung BML seemed to be predisposing clinical factors. For the imaging findings, posterior vertebral body invasion with bony destruction, neural foramen invasion, and canal encroachment were shown as common denominators. Especially in MRI findings, low T1 and T2 signal intensities with strong homogeneous enhancement were their common features. Conclusion: We gathered the fragmentary information of the spine BML for the first time, especially the MRI findings. Although spine BML is rare, it surely exists. Accordingly, spine surgeons should be suspicious of spine BML given its typical clinical history and MRI findings.