Solitary fibrous tumor/hemangiopericytoma is an uncommon vascular lesion with pericyte differentiation. It can occur anywhere in the body. Most of the lesions are benign but the behavior is unpredictable. This study aimed to describe the presentation, diagnosis, and treatment of solitary fibrous tumors with a review of the literature. The difficulty of making an accurate diagnosis is highlighted. This is a case report of a 30-year-old woman who was admitted to the hospital with abdominal pain.

Background: Forkhead box O 3a is a transcription factor, a member of the Forkhead box O family. It has a crucial role in both oncogenesis and tumor suppression. Cellular localization and phosphorylation status are considered to be prognostic factors for cancers. Loss of Forkhead box O 3a was found in various cancers. However, its mechanism in prostate cancer remains unclear. Objective: To analyze Forkhead box O 3a as prognostic biomarker potential in prostate cancer. Methods: This analytical study was done with a cross-sectional design. The population was all cases of primary prostate cancer from the Anatomical Pathology Department in West Sumatera. The sample was 56 slides and paraffin blocks with adequate tumor tissue. Hematoxylin and eosin-stained slides were evaluated to review Gleason score. The immunohistochemistry staining of Forkhead box O 3a on paraffin blocks was carried out to analyze protein expression semi-quantitatively. Positive expression was moderate to strong interpretation. Results: The highest proportion of prostate cancer was high-grade Gleason score (8-10) 76.79% cases. The positive Forkhead box O 3a expression on tumor cells was 51.79%, predominantly in the cytoplasm. The negative expression in the high-grade Gleason score was more than positive. Statistically, these results showed a negative significant correlation of Forkhead box O 3a expression and Gleason score (p=0.038). Conclusion: Forkhead box O 3a was likely to be deactivated in prostate cancer. Abstain expression in nuclear, but overexpression in the cytoplasm of tumor cells induces loss of tumor suppression function. Thus, Forkhead box O 3a has potential as a prognostic biomarker for prostate cancer.