Cotyledonoid Dissecting Leiomyoma of the Uterus: A Report of Four Cases

Abstract Introduction: Some variant forms of uterine leiomyoma with unusual infiltrative growth patterns have been known, including intravenous leiomyomatosis, diffuse leiomyomatosis, leiomyoma with vascular invasion, and disseminated peritoneal leiomyomatosis. Cotyledonoid dissecting leiomyoma was proposed as a new form of uterine leiomyoma with distinctive and alarming gross features resembling cotyledons of the placenta but with a benign histology. Cases: We report four new cases of this distinctive benign uterine tumor with unusual growth patterns. We aim to analyze the distinctive gross and histological features of cotylodonoid dissecting leiomyoma in order to avoid overtreatment of this benign tumor, especially for patients of reproductive age. All the patients in our series were of reproductive or perimenopausal age (range 36–51 years), and had an enlarged uterus or a pelvic mass and abnormal uterine bleeding. On gross examination, the lesions had an unusual appearance and were often lobulated with irregular margins. One of the four cases had no intramural insertion and typically presented as numerous exophytic congested small nodules resembling placental cotyledons. On microscopic examination, one of the four cases demonstrated only a cotyledonoid exophytic component with no evident mural dissection. Another case displayed an epithelioid cytological pattern. The two remaining cases were accompanied by limited foci of endometriosis and endosalpingiosis respectively. Conclusion: The recognition of this benign and unusual-appearing variant of leiomyoma by surgeons and pathologists is mandatory in order to avoid overtreatment and preserve fertility in young women. (J GYNECOL SURG 29:23)