Fine needle aspiration cytology of low grade endometrial stromal sarcoma: a case report.

Background: Endometrial stromal sarcoma (ESS) is a rare neoplasm and is composed of E cells closely resembling normal proliferative endometrial stromal cells. Because of its rarity, the preoperative diagnosis is difficult for clinicians. These tumors are rarely subjected to fine needle aspiration (FNA), and the cytologic diagnosis is also difficult, as the differential diagnosis is leiomyosarcoma/cellular leiomyoma.

Case: A 23-year-old woman presented with a history of prolonged vaginal bleeding. The diagnosis on FNA was given as sarcoma with the possibility of low grade ESS or leiomyosarcoma. On histopathologic examination, the diagnosis was confirmed to be low grade ESS.

Conclusion: Aspirates of low grade ESS are extremely cellular, with cohesive tissue fragments of monotonous, small, oval cells with bland chromatin tightly women in a metachromatic, extracellular matrix. The differential diagnosis should include a cellular leiomyoma and leiomyosarcoma.