Clear cell tumors of the ovary are frequently associated with ovarian endometriosis. Clinicopathologically, it has been suggested that clear cell tumors develop from endometriosis, but there has been little molecular evidence supporting this speculation. Microarray analysis revealed recently that hepatocyte nuclear factor1beta (HNF-1beta) was significantly upregulated in clear cell carcinoma of the ovary. In the present study, we examined 30 clear cell tumors (26 malignant, three borderline, and one benign) and 40 endometriotic cysts to clarify if differentiation into the clear cell lineage already begins in ovarian endometriosis. All of the 30 clear cell tumors, including borderline and benign ones, showed immunohistochemical expression of HNF-1beta in the nucleus, while other types of ovarian epithelial tumors (endometrioid, serous, mucinous, and Brenner tumors) rarely expressed it. Among 30 clear cell tumors, 17 (56%) cases were associated with endometriosis, and endometriotic epithelium was identified in 12 cases. In nine of the 12 cases, distinct nuclear immunostaining for HNF-1beta was detected in the endometriotic epithelium, as well as in the clear cell tumor. HNF-1beta expression was observed either in atypical endometriosis (four cases), or in endometriosis of a reactive nature (five cases). Furthermore, 16 of 40 (40%) endometriotic cysts without a neoplasm also expressed HNF-1beta, and the expression was almost exclusively observed in the epithelium showing inflammatory atypia. Our results indicate that HNF-1beta is an excellent molecular marker for ovarian clear cell tumors, including benign, borderline and malignant lesions. Early differentiation into the clear cell lineage takes place in ovarian endometriosis, not only in atypical endometriosis, but also in endometriosis with degenerative and regenerative changes, and this is probably responsible for the frequent occurrence of clear cell carcinoma in ovarian endometriosis. Keywords: ovary; clear cell tumor; endometriosis; hepatocyte nuclear factor-1beta; histogenesis Among malignant epithelial tumors of the ovary, clear cell carcinomas, as well as endometrioid adenocarcinomas, are most frequently associated with ovarian endometriosis. The frequency of endometriosis is reportedly between 21 and 54% in large series of clear cell carcinomas. [1][2][3][4][5] In addition, an atypical glandular change in endometriosis, the socalled atypical endometriosis, is often present associated with clear cell carcinomas, while it is rare in endometriosis without a neoplasm. 2,6,7 Thus, many clinicopathological studies have strongly suggested a malignant transformation of endometriosis to clear cell carcinomas, but little molecular evidence exists to support the notion that endometriosis is the precursor of clear cell carcinomas. A molecular genetic study showed that ovarian endometriosis and its adjacent carcinoma shared a common allelotype; however, few clear cell carcinomas were subjected to this study. 8 Recently, a study using an oligonucleotide array technique...

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Small cell carcinomas of the uterine cervix are rare tumors with an aggressive behavior. Although these tumors can exhibit neuroendocrine differentiation, the criteria for neuroendocrine differentiation are subjective and not well defined. In this study, the authors tentatively defined small cell neuroendocrine carcinoma (SCNEC) as a tumor composed of small cells with at least two of the following: argyrophilic cytoplasm, chromogranin A immunoreactivity, and synaptophysin immunoreactivity. We found 10 cases fulfilling these requirements. Five of the 10 tumors were composed mainly of small ("oat") cells and 5 of mainly larger "intermediate" cells. The majority of both subtypes showed an insular pattern. Three of the 10 SCNECs were pure, whereas the other seven were mixed with adenocarcinoma and/or squamous cell carcinoma or cervical intraepithelial neoplasia. In addition to the definitional markers noted earlier, the tumors were immunoreactive for serotonin (6 cases), somatostatin, gastrin, glucagon, and pancreatic polypeptide. No tumors were immunoreactive for cytokeratin 20. Human papillomavirus (HPV)-18 was detected in all of the pure tumors and both the SCNEC and adenocarcinomatous components in four of the mixed tumors. No other types of HPV were detected. The tumors showed a relatively low frequency of loss of heterozygosity for representative tumor suppressor gene sites; p53 mutations were found in only one case.