Objective: Uterine adenosarcoma has low malignant potential, except in cases with sarcomatous overgrowth (SOG) and a high-grade morphology. We here point out the prognostic clinicopathological and immunohistochemical features as well as the microsatellite instability (MSI) status of high- and low-grade adenosarcomas.

Material and Method: In this study, DNA mismatch repair proteins, p16, cyclin D1, ER, PR, and CD10 were examined in uterine adenosarcoma cases using immunohistochemistry. The association between these proteins and clinicopathological parameters was also evaluated.

Results: ER, PR and CD10 expressions were lower and weaker in high-grade adenosarcomas with SOG compared to low-grade adenosarcomas without SOG (p < 0.05). p16 positivity was more frequent in high-grade adenosarcomas than low-grade adenosarcomas (p < 0.05). There was no statistically significant difference between cyclin D1 positivity, MSI, and other clinicopathological parameters (p ≥ 0.05). Cyclin D1 positivity and loss of CD10 expression were associated with shorter disease-free survival (DFS). Loss of ER and CD10 expression was associated with shorter overall survival (OS) (p < 0.05). MSI was not associated with DFS or OS (p ≥ 0.05).

Conclusion: These results suggested that p16 positivity, and loss of ER, PR, and CD10 expression were predictors of high-grade morphology. Additionally, the current study showed that cyclin D1-positive tumors had high recurrence rates; however, no significant relationships were found between MSI and DFS or OS in patients with uterine adenosarcoma. Further investigations are required to determine the importance of p16, cyclin D1, and MSI in uterine adenosarcomas.