To establish an immunohistochemical profile of presumed female adnexal mesonephric tumours (FATWO) for diagnostic purposes and to compare the findings with those of mesonephric and paramesonephric derivatives in order to establish supportive evidence for a mesonephric origin.
Standard immunohistochemistry was performed on formalin-fixed tissues. Tumours, mesonephric remnants and paramesonephric structures generally show positive staining for vimentin, CAM 5.2 and cytokeratins 7 and 19 but are negative for CK20 and 34βE12. EMA is positive in both mesonephric and paramesonephric derivatives but is negative in the tumours. Glutathione S-transferase μ (GSTµ) is generally positive in both tumours and mesonephric derivatives but negative in paramesonephric structures.
Immunohistochemistry plays little part in the diagnosis of FATWO. The tumours are generally cytokeratin and vimentin-positive and EMA-negative. GSTµ, as a marker for the mesonephric duct, is a useful adjunct. Our findings of the study support but do not prove that FATWOs are of mesonephric origin.