Extra-ovarian cellular fibroma: A case report and review of the literature

Extra-ovarian sex cord-stromal tumors are often clinically and radiologically considered as ovarian malignancies. Pathologically, this poses a diagnostic challenge. Here, we present a case of extra-ovarian cellular fibroma in an eighty-four-year-old woman. The pedunculated solid mass was located in the posterior cul-de-sac, and intraoperative frozen section diagnosis was leiomyoma or fibroma. Both ovaries and salpinges were normal. A laparoscopy-assisted mass excision and bilateral salpingo-oophorectomy were performed. Microscopically, cellularity showed increased alternative pattern, mild cytological atypia, and the mitotic count was 2/10 high-power fields. Tumor cells were immunoreactive to antibodies produced against Wilms tumor-1 and progesterone receptors. The cells were weakly positive for inhibin-alpha and smooth muscle actin. The pathological diagnosis was an extra-ovarian cellular fibroma. We summarized the cases of extra-ovarian pure stromal tumors reported to date and compared them with our case. Immunohistochemical studies are essential because the pathological differential diagnosis of extra-ovarian fibromas includes extra-gastrointestinal stromal tumors and leiomyomas. Cellular fibromas should be carefully diagnosed due to their tendency to recur.