According to literature approximately 60% from all ovarian malignances express epithelial phenotype. According to their histomorphological characteristics, epithelial ovarian
tumors are divided into eight groups. In some particular cases, separate histological types are hard to distinguish one from another. Recent studies show the presence of beneficial effect of
adjuvant radiotherapy on most of the early ovarian
carcinomas (all, except serous
carcinomas). In
renal cell carcinomas SI00A 1 is used to distinguish between different subtypes of the
malignancy. Forty cases of ovarian
carcinomas were analyzed in a retrospective study. Immunohistochemical evaluation of the
S100A1 protein expression was carried out on representative archival
formalin -fixed -
paraffin-embedded tissue materials. Positivity for S100A1 was observed in 31 (77.50%) of the studied cases. Twenty-seven out of thirty-two (84.38%) cases of serous ovarian
carcinoma were found to express S100A1. S100A1 expression was observed in one out of the two mucinous and three out of the six endometroid ovarian
carcinomas. Immunopositivity was nuclear, cytoplasmic or nuclear and cytoplasmic in serous
carcinomas, nuclear in the one positive
mucinous carcinoma and sytoplasmic in the three imunopositive endometroid ovarian
carcinomas. The S100A1 immunohistochemical marker is not likely to be useful in clinical practice to distinguish between different histological subtypes of
ovarian cancer. The large percentage of S100A1 positivity in serous ovarian
carcinomas needs a better understanding.