Objective: Distinction of endometrial stromal sarcoma (ESS) from benign smooth muscle proliferations like cellular leiomyoma (CL) is sometimes problematic. The purpose of this study was to evaluate the potential utility of a panel of antibodies in the differential diagnosis of ESS and CL.
Methods: Using a standard streptavidin-biotin method, the expression of desmin, alpha smooth muscle actin (SMA), calponin h1, h-caldesmon, estrogen receptor (ER), progesterone receptor (PR), CD10, CD44v3, proliferating cell nuclear antigen (PCNA), and mast cells (MCs) were evaluated in 26 cases of ESS (21 low grade, 5 high grade), 25 CL (17 common CL, 8 highly CL), 25 myometria, and 25 endometria.
Results: Among ESS, 20 of 26, 17 of 26, 9 of 26, 12 of 26, 14 of 26, and 22 of 26 were positive for expression of desmin, SMA, calponin h1, ER, PR, and CD10, respectively, while only 2 of 26 were positive for CD44v3 and all were entirely negative for h-caldesmon. Of CL, all were positive for SMA, calponin h1, PR, and CD44v3; 24 of 25, 24 of 25, and 19 of 25 were positive for desmin, h-caldesmon, and ER, respectively, whereas 1 of 25 focally marked with antibodies to CD10. There was no significant difference of PCNA expression between ESS and CL, although the ESS cases tended to have higher values. The MC counts were significantly higher in the CL group than in the ESS group (P < 0.01). When using the cut-off value of seven MCs per HPF to distinguish ESSs from CLs, the sensitivity and specificity of this cut-off value were 92.9% and 100%, respectively.
Conclusions: A panel of h-caldesmon, CD10, and CD44v3 should be used and will distinguish ESS from CL in most cases. In addition, counting the number of MCs might be useful as part of a multivariate approach to the differential diagnosis of them. But the biological function of MC and CD44v3 in these tumors is worthy of further investigation.