Serous Tubal Intraepithelial Carcinoma (STIC)-like Lesions Arising in Ovarian Serous Cystadenofibroma: Report of 2 Cases.

Recent studies have demonstrated that most so-called ovarian high-grade serous carcinomas are likely to arise from the epithelium of the distal fimbrial portion of the fallopian tube from a precursor lesion known as serous tubal intraepithelial carcinoma (STIC). We report 2 cases in patients aged 56 and 71 of lesions morphologically identical to STIC (referred to as STIC-like lesions) arising from the benign ciliated epithelium of ovarian serous cystadenofibromas. In 1 case, 2 glands within the serous cystadenofibroma exhibited high-grade nuclear atypia and mitotic activity and in the other similar changes were multifocal. No invasion of the stroma was seen. In both cases, the STIC-like lesion exhibited aberrant "mutation-type" staining with p53 (1 diffuse intense positivity, 1 null pattern). As far as we are aware, a STIC-like lesion involving the epithelium of a benign ovarian serous neoplasm has not been reported previously. Both patients were followed up without adjuvant treatment. One case is recent, and follow-up in the other patient is uneventful at 12 mo.