Mucosubstances in classification of serous and mucinous ovarian tumors: a morphometrical study

Mucinous adenocarcinoma developed from human fallopian tube epithelial cells through defined genetic modifications

Recent studies have suggested that some ovarian and pelvic serous carcinomas could originate from the fimbriated end of the distal fallopian tube. To test this hypothesis, we immortalized a normal human fallopian tube epithelial (FTE) cell line by using retrovirus-mediated overexpression of the early region of the SV40 T/t antigens and the human telomerase reverse transcriptase subunit (hTERT). These immortalized FTEs were then transformed by ectopic expression of oncogenic human HRAS (V12) . Tumorigenicity of the immortalized and/or transformed cells was subsequently tested by anchorage-independence growth assay and inoculation into nude mice via subcutaneous and intraperitoneal injection. As expected, the HRAS (V12) -transformed FTEs produced tumors through both subcutaneous and intraperitoneal injections, whereas no tumor growth was observed in immortalized FTEs. Unexpectedly, histopathological examination of tumors resulting from subcutaneous as well as intraperitoneal injections revealed largely poorly differentiated mucinous adenocarcinoma mixed with undifferentiated carcinoma. The tumor implants invaded extensively to the liver, colon, spleen, omentum, adrenal gland and renal capsule. Immunohistochemical staining of tumor cells showed positive staining for the epithelial cell markers cytokeratin AE1/AE3 and Müllerian lineage marker PAX8. Our study demonstrates that FTEs can generate poorly differentiated mucinous adenocarcinoma mixed with undifferentiated carcinoma through genetic modifications. Thus, we provide the first experimental evidence that fimbrial epithelial cells of the fallopian tube could be a potential source of ovarian mucinous adenocarcinoma.

CA125 and thyroglobulin staining in papillary carcinomas of thyroid and ovarian origin is not completely specific for site of origin

AIMS

A 70-year-old woman presented with metastatic psammoma body-rich papillary carcinoma in a supraclavicular lymph node. No primary site was evident. The tumour showed strong staining for CA125 and weak staining for thyroglobulin. Prompted by this case we aimed to assess the reliability of immunostaining for CA125 and thyroglobulin in making the distinction between thyroid and ovarian papillary carcinoma.

METHODS AND RESULTS

Nine papillary carcinomas of the thyroid and 17 serous papillary carcinomas of the ovary were stained for CA125 and thyroglobulin, as well as CAM 5.2, LP 34, carcinoembryonic antigen (CEA), S100 and diastase/periodic acid-Schiff. Nine of nine thyroid carcinomas stained for thyroglobulin; in addition CA125 was positive in four of nine. Normal surrounding thyroid also showed some reaction. Seventeen of 17 ovarian serous carcinomas were positive for CA125; in addition one case showed moderately strong staining for thyroglobulin. Mucin stains were positive in 14/17 ovarian serous carcinomas, but negative in all thyroid carcinomas. The other antibodies assessed showed no useful differences in staining frequency.

CONCLUSION

Many cases of papillary carcinoma of the thyroid show CA125 staining, and this feature therefore has little positive predictive value for an ovarian origin. Occasional cases of ovarian papillary carcinoma may show staining for thyroglobulin, and this result should therefore be interpreted cautiously.