Clinicopathological and immunohistochemical analysis of 23 cases of ovarian cellular fibroma

Abstract

Objective: To define clinicopathological characteristics and immunohistochemical markers helpful in differentiating between cellular fibroma (CF) and mitotically active cellular fibroma (MACF). Method: Patient records and archival pathology specimens of 23 ovarian cellular fibromas diagnosed and followed between 2000 and 2012, were reviewed and immunohistochemistry was performed. Results: The mean age of patients with CF (n=15) and MACF (n=8) was 55 and 37 years, respectively. All tumours were unilateral, with a mean tumour size of 8.6 cm for CFs and 12.9 cm for MACFs. In all tumours, most of the cells showed mild or moderate nuclear atypia. The mean highest mitotic count was 2.0 MFs/10 HPFs for CF, and 7.2 MFs/10 HPFs for MACFs. The majority of the tumours were immunoreactive for vimentin, alpha-SMA, WT-1, inhibin-alpha, calretinin, CD56, melan-A, PR, and bcl-2, and negative for pan-cytokeratin, EMA, CD117, ER, and p53. A few tumours were also positive for S100, desmin, CD10, and CD99. In addition, the MIB-1 labeling index (LI) in MACFs was higher (mean 16.9 %, range 12–25 %), than that in CFs (mean 5.9 %, range 3–9 %). Conclusion: Our results confirm the clinicopathological differences and the immunophenotypic similarity between ovarian fibromas and cellular fibromas, and suggest that the use of MIB-1 LI may help in differentiating between CF and MAFC.