Notes on the morphological features of cotyledonary dissecting leiomyoma, which is rare in clinical practice.

Benign uterine leiomyoma (U.LMA) and malignant uterine leiomyosarcoma (U.LMS), which are both uterine mesenchymal tumors, are distinguished by the number of cells with mitotic activity. However, uterine mesenchymal tumors contain tumor cells with various cell morphologies; therefore, making a diagnosis, including differentiation between benign tumors and malignant tumors, is difficult. For example, A cotyledonoid dissecting leiomyoma is a uterine leiomyoma with a very rare placental lobed tissue morphology that can be misdiagnosed as a malignant uterine leiomyosarcoma because of its rarity and characteristic appearance on gross examination. Similar to the detection of a suspicious malignant mass during MRI imaging examination by medical staff, healthcare professionals must understand the characteristic appearance of a cotyledonoid dissecting leiomyoma. Clinicians and pathologists must understand the oncologic features of cotyledonoid dissecting leiomyoma to prevent misdiagnosis of malignancy and consequent overtreatment.