Clear cell borderline tumor without fibromatous component: Pathological and literature review and report of two cases.

The aim of the present study was to examine the clinical outcome of ovarian clear cell borderline tumor (CCBT) through pathological review for cases with clear cell carcinoma (CCC) and CCBT between 1984 and 2015 who received surgery at the National Defense Medical College Hospital using 2020 World Health Organization (WHO) criteria. In addition to the definition of CCBT in 2020 WHO criteria, clear cell with atypia of the glandular epithelium without fibromatous component was added to the diagnostic criteria of CCBT. Two cases with CCBT were identified through review in the current study. There were no cases that changed from the initial CCBT diagnosis that were included in the current study. Case 1 was a 43-year-old woman who received total hysterectomy, bilateral salpingo-oophorectomy and partial omentectomy. Pathologically, cysts were lined by cuboidal, hobnail and clear cells with eosinophilic cytoplasm and moderate nuclear atypia without the fibromatous component. These cells were adjacent to atypical endometriosis and non-atypical endometriosis, and the patient was diagnosed with CCBT. She exhibited no evidence of the disease for 37 months following surgery. Case 2 was a 42-year-old woman who received left salpingo-oophorectomy, partial omentectomy and pelvic lymphadenectomy. The tumor exhibited a cyst (80 mm) and nodular component. Pathologically, the tumor cells were lined by hobnail cells with mild atypia and eosinophilic cytoplasm without the fibromatous component. This patient was diagnosed with CCBT and exhibited no evidence of disease for 20 months following surgery. CCBT without fibromatous component is a rare and non-aggressive histological subtype. Additionally, regardless of fibromatous component, CCBT was able to be diagnosed.