Clear Cell Carcinoma

Clear cell carcinoma is an uncommon variant of endometrial carcinoma, and clinico-pathological studies have produced conflicting results regarding its biological behavior, with 5-year survival ranging from 21 to 75% (19-22). Furthermore, in addition to tumors that are pure clear cell carcinoma, clear cell differentiation can be admixed with tumors demonstrating endometrioid or serous components. Although, clear cell carcinoma is often categorized as a Type II tumor both the discrepancy in the biological behavior and its association with endometrioid and serous carcinoma suggests the possibility that it may not fit simply into the dualistic model of endometrial carcinoma.

Recent immunohistochemical studies using p53, Ki67, estrogen and progesterone receptors that were performed on clear cell carcinoma have suggested that they are different from either endometrioid or serous carcinoma (23). A recent molecular study demonstrated that the majority of pure clear cell carcinomas do not show mutations in either PTEN or TP53; the most commonly altered genes in type I and type II tumors, respectively (24). Furthermore, in tumors with a mixed histological appearance, the mutations present in the serous or endometrioid component were identical to those found in the clear cell component supporting a monoclonal origin of the distinct components (Fig. 2). These findings suggest that clear cell carcinoma may arise through different pathogenetic pathways, thus explaining the wide range of biological behavior. The absence of mutations in the PTEN gene and the TP53 gene in the majority of pure

Table 1

Mutational Frequencies for TAM and NO-TAM Endometrial Cancers

Table 1

Mutational Frequencies for TAM and NO-TAM Endometrial Cancers

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