An occult leiomyosarcoma in a hysterectomy specimen presumed to be uterine fibroid preoperatively: A case report

Abstract

Uterine sarcomas account for approximately 1% of all gynecologic neoplasm and 3–7% of all uterine cancers. Approximately 1 in every 800 women believed to have a leiomyoma actually has a sarcoma. Here we discuss a case of occult leiomyosarcoma in a hysterectomy specimen suspected to be uterine fibroid preoperatively along with spectrum of diagnoses of uterine mesenchymal tumours and the differentiating parameters. This is a descriptive study. A 48-year-old female with heavy menstrual bleeding since 4-5 years, on USG showed an enlarged uterus containing a fibroid with degenerative changes. Grossly, fibroid is seen (11cm x 8.6cm) greyish white, fleshy, involving more than half of the myometrium. Microscopically, fibroid mass showed highly pleomorphic, hyperchromatic tumour cells with dispersed chromatin and indistinct cytoplasm, arranged in intersecting fascicles. Large areas of coagulative tumour cell necrosis seen, mitotic figures > 10 per 10 HPF, suggesting leiomysarcoma of uterus. Leiomyosarcomas are diagnosed when a triad of histopathological features is seen - significant atypia, increased mitotic activity and coagulative tumour cell necrosis. These are important in differentiating between variants of leiomyoma, STUMP and leiomyosarcoma. Sometimes a benign fibroid-like mass can incidentally be diagnosed as leiomyosarcoma microscopically. It’s essential to avertmorcellation in routine gynecological practice especially in perimenopausal women with a large fibroid to avoid intra-abdominal dissemination. Precise pre-operative radiological workup by MRI or expert-guided sonogram is also suggested but given the complexities involved, role of histopathology to diagnose leiomyosarcoma is invaluable.