[1145] Immunohistochemistry for the Imprint Gene Products TSSC3 To Facilitate Differential Diagnosis of Trophoblastic Diseases

Masaharu Fukunaga. Jikei University Daisan Hospital, Komaeshi, Tokyo, Japan

Background: Differentiation between trophoblastic diseases, complete mole (CM), partial mole (PM), invasive mole (IM), hydropic abortion (HA), placental site trophoblastic tumor (PSTT), epithelioid trophoblastic tumor (ET), and choriocarcinoma (CC) is very important for patient management. Maternally expressed genes are critical for embryonic development and paternally expressed genes are critical for placental development.
Design: TSSC3 is one of the paternally imprinted, maternally expressed genes. TSSC3 is the most markedly suppressed among 13 transcribed genes from a maternal allele. It is said to be related to trophoblastic differentiation. In order to determine whether immunohistochemistry of TSSC3 can be used as a tool for the differential diagnosis of trophoblastic diseases, 40 CMs (including one putative CM case, 3 cases of CM/normal twins and one case with invasive mole), 23 PMs, 18 Has, 8 PSTTs, 2 ETTs, and 7 CCs were stained by immunohistochemistry for TSSC3.
Results: All PMs and HAs were positive for TSSC3. There was strong TSSC3 staining of the cytoplasm or nuclei in the villous cytotrophoblasts. All CMs except one putative case were completely negative in the villous cytotrophoblasts. It was expressed in cytotrophoblasts in normal villi of 3 cases of CM/normal twins. One putative CM case, in which some villi showed histologically typical CM features and other villi showed edema with stromal cell hyperplasia and the absence of trophoblastic hyperplasia, exhibited a biphasic pattern, typical CM-type negative staining in CM villi, and positive staining in cytotrophoblasts in non-CM areas. Some villi exhibited a mosaic pattern. Placental site intermediate trophoblasts were rarely positive for TSSC3 in limited cases. A small number of tumor cells in 5 of 8 PSTTs and 1 of 2 ETTs were positive for TSSC3. Syncytiotrophoblasts were focally positive for TSSC3 in 2 of 7 CCs.
Conclusions: Immunohistochemistry for TSSC3 serves as a practical and reliable diagnostic marker for the discrimination of CM from PM, especially for CM/normal twin cases, and CM from HA. TSSC3 is not useful for the differential diagnosis among PSTT, ET, and CC. One putative CM case may be due to androgenic/biparental chimera or a mosaic, although molecular cytogenetic analysis is necessary.
Category: Gynecologic & Obstetrics

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 136, Tuesday Morning


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