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[Primitive neuroectodermal tumor in female genital tract: a clinicopathologic study].

OBJECTIVE
To study the clinicopathologic features of primitive neuroectodermal tumor (PNET) in female genital tract.


METHODS
Six cases of PNET arising in female genital tract were retrospectively reviewed. The clinicopathologic features, immunohistochemical findings and EWS gene translocation study results were analyzed.


RESULTS
The age of patients ranged from 10 to 27 years (mean = 20 years). The sites of involvement included ovary (1 case), uterus (1 case), vulva (2 cases) and vagina (2 cases). The greatest diameter of the tumor ranged from 2 to 10 cm (mean = 5.4 cm). The tumor had nodular appearance and showed grayish-pink fleshy cut surface, accompanied by foci of hemorrhage and necrosis. Histologically, the tumor was composed of malignant small round cells with indistinct cell borders, hyperchromatic nuclei, dense chromatin, tiny nucleoli and scanty cytoplasm. The tumor cells were arranged in sheets or lobules. Homer-Wright rosettes were identified in 1 case. Immunohistochemical study showed that the tumor cells were positive for CD99, FLI-1 and CD56 (6/6). Focal expression of vimentin (5/6), NSE (5/6), nestin (4/6), synaptophysin (4/6), S-100 protein (2/6) and chromogranin A (1/6) was also demonstrated. EWS gene translocation was detected in 5 cases studied. Follow-up information was available in 2 patients (7 and 17 months of follow up, respectively). One of them died of tumor metastasis 17 months after diagnosis. The other patient was still alive.


CONCLUSIONS
PNET arising in female genital tract is rare. It mainly involves ovary, uterus, vulva and vagina. Immunohistochemical study using a panel of antibodies and fluorescence in-situ hybridization play an important role in definitive diagnosis of this rare malignancy.