Aim: To determine the incidence of malignancy and fibroid variants at surgery for presumed benign symptomatic fibroids, and to evaluate clinical outcomes following morcellation.

Methods: 10 year retrospective audit of hysterectomy and myomectomy procedures for symptomatic fibroids with review of histopathology.

Results: From 2004-2013, 1115 hysterectomies and 376 myomectomies were performed under the Gynaecology 1 Unit for presumed benign disease at the Royal Women’s Hospital.

Clinical history and histopathology review of these yielded 1149 cases of symptomatic fibroids. Unexpected gynaecological malignancies included 3 cases of endometrial stromal sarcoma (ESS - 0.26%), no cases of leiomyosarcoma, one case of endometrioid adenocarcinoma of the endometrium and one case of adenosarcoma of the endocervix. The rate of ESS was comparable to other findings in the recent literature. There were also three cases of unexpected non-gynaecological malignancies. Overall, 0.70% of cases had an unexpected malignancy. Furthermore, 4 smooth muscle tumours of uncertain malignant potential (STUMPs - 0.35%) and 55 cases (4.8%) of benign fibroid variants were also identified.

All of the malignancies and STUMPs were referred to relevant Oncology Units and received follow up and further treatment as appropriate.

As a secondary aim, the incidence and outcomes of morcellation were evaluated. 712 cases (62.0%) involved morcellation (542 [47.2%] manual; 68 [5.9%] power; 102 [8.9%] hysteroscopic). Two of the gynaecological cancer cases involved manual morcellation to optimize surgical access and did not result in upstaging of the cancer. One of the four cases of STUMPs involved manual morcellation, but none have had documented disease recurrence to date.

Of note, two cases of cellular leiomyoma involving manual morcellation at open surgery subsequently represented with clinically significant disease – one with life-threatening intracardiac leiomyomatosis and another with benign metastasizing leiomyomatosis to the lung. This rate was higher than expected (10% of cellular fibroid variants).

Conclusion: In our study population, there was a low but significant rate of unexpected uterine malignancy in surgery for benign fibroids consistent with recent studies, and a higher than expected incidence of clinically significant disease associated with benign fibroid variants. Clinical outcomes may be affected by morcellation and may have been observed in a small proportion of cases of benign fibroid variants.