Uterine leiomyoma with bizarre nuclei – A series of four cases

Uterine leiomyoma is the most common benign mesenchymal tumor of the uterus occurring in females of reproductive age group and are derived from smooth muscle. Degenerative changes are usual in leiomyoma. There is a wide spectrum of morphological patterns in leiomyomas, among them 90% of leiomyomas are the conventional type or usual type. Leiomyoma with bizarre nuclei is an unusual variant of uterine leiomyoma with presence of marked nuclear atypia and pleomorphism. However, there is low mitotic activity (< 5 mitoses/10 high power fields), absence of tumor cell necrosis and intermixed normal spindled smooth muscle cells. The present study describes histopathological analysis of 4 cases of leiomyoma with bizarre nuclei. All these cases underwent abdominal hysterectomy for leiomyomas in the uterus. The age range was 47 to 52 years. On gross examination the cases had well-defined masses with grey white, whorled areas and microscopic impression was leiomyoma with bizarre nuclei. These cases had low mitotic activity ranging from 1 to 3/ 10 high power fields and absence of tumor necrosis. Ki 67 index was 0.5 -1.0%. Leiomyoma with bizarre nuclei can create a diagnostic dilemma due to marked nuclear atypia, multinucleated tumor cells and karyorrhectic cells resembling mitotic figures. Hence it is important to rule out more aggressive and malignant mesenchymal tumors.