Low-grade endometrial stromal sarcoma with extensive sex cord differentiation, heterologous elements, and complex atypical hyperplasia: Case report and review of literature

- Endometrial stromal sarcoma (ESS) may have sex cord differentiation, usually focal.
- Diagnosis of ESS is difficult when variant morphology predominates.
- Prognosis differs between ESS and UTROSCT; therefore, distinction is critical.
- Extensive tumor sampling is mandatory to identify neoplastic endometrial stroma.
- Sex cord differentiation may be associated with endometrial hyperplasia.