Loss of dystrophin is common in uterine leiomyosarcoma: a potential biomarker for clinical application

Uterine leiomyosarcoma (LMS) is a deadly disease with high rates of recurrence and a poor prognosis. Its tumorigenesis remains largely unknown, and no specific biomarkers can be used for the differential diagnosis of LMS from other mimics. Recent whole-genome studies revealed a loss of dystrophin is common in LMS, especially in uterine LMS. To investigate the expression pattern of dystrophin expression across different types of uterine smooth muscle tumors, immunohistochemistry was performed, including usual-type leiomyoma, fumarate hydratase-deficient leiomyoma, leiomyoma with bizarre nuclei, conventional LMS, and normal myometrium for this study. To further evaluate the genomic change in dystrophin gene region, whole-genome sequencing in 10 LMS cases were analyzed. Dystrophin expression was detected in 94% (45/48) of myometrium, 97% (34/35) of usual-type leiomyoma, 84% (26/31) of fumarate hydratase-deficient leiomyoma, 60% (12/20) of leiomyoma with bizarre nuclei, and 18% (6/34) of LMS. Loss of dystrophin expression was significantly different between benign and malignant tumors (LMS cases counted as malignant only) (p < 0.01). Of note, copy number loss in the dystrophin genomic region was found in all 10 cases of LMS. Additionally, patients with dystrophin-positive LMS tend to have a better overall survival than patients with dystrophin-negative LMS.