Mitotically Active Cellular Fibroma of the Ovary Recurring after the Longest Interval of Time (16 yr): A Challenging Case with Systematic Literature Review

Cellular fibromas represent 10% of ovarian fibromas. Mitotically active cellular fibromas show mild nuclear atypia but ≥4 mitoses/10 high-power fields: the clinical course is usually uneventful but literature review is lacking. A 34-yr-old woman underwent left oophorectomy for a 9-cm ovarian mitotically active cellular fibroma at another hospital. The tumor was cellular (spindle cells in fascicular and storiform patterns) revealing mild atypia and 4 nonatypical mitoses/10 high-power fields without necrotic areas. After 16 yr, the tumor recurred as a 5-cm peritoneal nodule on the anterior sigmoid wall near the sigmoid-rectal junction. Frozen section revealed a spindle cell tumor invading the intestinal tunica muscularis propria: a gastrointestinal stromal tumor was favored as previous history was unavailable at that time. Intestinal resection was performed: no residual tumor was found. The patient was followed-up for 8 yr without further recurrences. The peritoneal nodule showed 2 mitoses/10 high-power fields and pericellular reticulin staining. The tumor was variably positive for vimentin/bcl-2/melan-A/CD56/ER/PR/α-inhibin/CD10/calretinin, focally positive for desmin, negative for pan-cytokeratin/actin/EMA/CD34/HMB45/CD117/CD99/S100/synaptophysin. The Ki67-index was 9%. To our systematic literature review, 7 additional recurrent cases were reported. We describe a mitotically active cellular fibroma recurring after the longest interval of time. Extensive sampling of difficult cases should exclude malignant areas. Moderate nuclear atypia, tumor rupture, adhesions to pelvic/abdominal organs, infarction with extraovarian involvement, and incomplete excision may lead to relapse but there are conflicting data: prolonged follow-up can be suggested in these cases.