The
estrogen receptor content, determined immunohistochemically by staining with
monoclonal antibodies, was studied in seven consecutive cases of
endometrial stromal sarcoma. In addition, the mitotic rate and immunohistochemical patterns (
vimentin,
desmin, actin, cytokeratins) were determined. Five of seven cases contained
estrogen receptors, three low-grade (fewer than 10 mitoses/10 high-power fields [hpf]) and two high-grade (10 or more mitoses/10 hpf), the latter having a relatively low mitotic rate. The two negative cases were high-grade with a very high number of mitoses.
Tumor cells were positive only to
vimentin. Based on these results, we postulate that
estrogen receptors are undetectable only in highly proliferating
neoplasms. Thus, immunohistochemically determined
estrogen receptor levels may indicate the aggressiveness of
endometrial stromal sarcoma, and might be a guideline in selecting patients for hormonal
therapy. The presence of positive immunostaining to
vimentin confirms the mesenchymal origin of
endometrial stromal sarcoma.