OBJECTIVETo study the morphologic feature, immunohistochemistry phenotype of ESS and its metastases, with emphasis on the histogenesis, tumor differentiation and diagnostic criteria.

METHODSThe pathologic features of 15 cases and 4 metastases were studied. The immunohistochemical study was performed on selected sections by a panel of antibodies including CD10, smooth muscle actin, estrogen and progesterone receptors, keratin (AE1/3) and alpha-inhibin.

RESULTSPatients were 22 to 75 years of age (mean 45). The endometrial stromal component predomominated in 7 cases. Three cases showed a picture of smooth muscle differentiation. Endometrial stromal sarcoma with fibromyxoid features were present in 2 cases. There were 3 sarcomas of poorly differentiated. The morphology features of the metastatic foci in 3 of the 4 metastasis cases were not similar to that of the primary counterpart in uteri. Among 14 ESS and 4 metastases, 15 of 18, 5 of 18, 7 of 18, and 10 of 18 were positive for CD10, SMA, ER and PR, respectively. AE1/3 and alpha-inhibin were only positive in the adenomatous area of ESS. Strong expression of SMA was obtained in all 10 cellular leiomyomas, and CD10 was only weakly expressed in 1 case (P < 0.05).

CONCLUSIONSESS are morphologically heterogeneous with multipotential differentiation. The histologic features of the metastases may not be similar to those of the primary. CD10 and SMA are diagnostically useful markers for ESS.