BACKGROUND The diagnosis of endometrial stromal sarcoma (ESS) is often difficult in cases showing diverse histological differentiation or in undifferentiated endometrial sarcoma (UES). Recently, JAZF1/JJAZ1 gene fusion has been described as a defining feature of low-grade ESS (LGESS). However, its prevalence is variably reported, and the diagnostic utility has rarely been examined for cases showing various histological differentiation. METHODS To test the diagnostic utility of JAZF1/JJAZ1 gene fusion in difficult cases, we compared the prevalence of the JAZF1/JJAZ1 fusion gene in LGESS with and without histological differentiation. RESULTS The JAZF1/JJAZ1 fusion transcript was detected in 18 of 21 LGESS (85.7%), including 14 classical LGESS (93%), four LGESS with diverse histological differentiation (67%), and two with UES (28.6%). Positive cases included two LGESS with sex cord-like differentiation, one with osseous differentiation, and two UES. LGESS showing smooth muscle differentiation revealed the fusion transcript only in the classic area. Direct sequencing analysis of two LGESS revealed a previously reported breakpoint at t(7;17)(p15;q21). CONCLUSIONS The JAZF1/JJAZ1 fusion gene was identified in a significant proportion of LGESS showing secondary histological differentiation except in cases with smooth muscle differentiation. Thus, this fusion gene may be useful to confirm the diagnosis in difficult cases of LGESS.
The authors report a case of uterine tumor resembling ovarian sex-cord tumor in a 31-year-old woman with emphasis on immunohistochemistry. Histologically this case showed identical features to a well-recognized endometial stromal tumor except for focal epithelial-like differentiation that resembled sex-cord tumors of the ovary. The sex-cord like differentiation of tumor cells were manifested by trabeculae, plexiform cords, and gland-like pattern. We diagnosed this case, according to the features described by Clement and Scully(1976), as uterine tumor resembling ovarian sex-cord tumor, group I. Although the histogenesis of this tumor is unclarified, most authors believe that this tumor may be originated from multipotent mesenchymal cells of the uterus. On immunohistochemical stains, Desmin was uniformly reactive in epithelial-like cells and in focal areas of endometrial stromal sarcoma-like component.
Vimentin was partly reactive in all tumor components, however EMA was non-reactive.
A case of low-grade endometrial stromal sarcoma resembling ovarian sex-cord tumor in the uterus of a 43-year-old woman is described. This tumor belongs to the group II category of uterine tumors resembling ovarian sex-cord tumor described by Clement and Scully, and the epithelial-like elements show prominent smooth muscle differentiation, proved by immunoreactivity for desmin and actin. The patient did not receive any adjuvant therapy; she is alive and well without recurrence 8 months postoperatively.