Diagnosis of endometrial stromal tumors: a clinicopathologic study of 25 biopsy specimens with identification of problematic areas.

OBJECTIVES To assess the difficulties associated with diagnosing endometrial stromal tumors (ESTs) on endometrial biopsy. METHODS We examined 25 endometrial biopsy specimens from 19 consecutive women diagnosed with either endometrial stromal nodule (n = 3) or endometrial stromal sarcoma (n = 16). RESULTS Rereview of the biopsy specimens revealed a stromal fragment suspicious for an EST in 16, of which eight had received a benign diagnosis on initial review. Most ESTs had an aglandular stromal fragment that was 5 mm or larger. Stromal fragments of this size were not encountered in the control material. Problematic areas included highly cellular leiomyoma and a lack of attention to the stromal compartment. CONCLUSIONS Most endometrial stromal tumors present with large aglandular stromal fragments (≥5 mm). These fragments are large enough that difficulties in diagnosis appear to be due to a lack of attention to the stromal compartment.