Ovarian clear cell adenofibromatous tumors. Benign, of low malignant potential, and associated with invasive clear cell carcinoma.

The authors have studied 17 cases of ovarian clear cell tumors having an adenofibromatous pattern and classified them on a histologic basis into three categories: benign, of low malignant potential, and associated with invasive clear cell carcinoma. Clear cell adenofibroma is characterized by orderly tubules and glands lined by uniform epithelium with little or no nuclear atypia set in an abundant stroma with an interlacing pattern resembling ovarian stroma. Clear cell adenofibromatous tumors of low malignant potential had a similar stroma, but exhibited moderate to marked degrees of epithelial proliferation and atypia. In the third category there were cases of invasive clear cell carcinoma in which a distinct portion of the tumor met the criteria for clear cell adenofibroma, or clear cell adenofibromatous tumor of low malignant potential. Cases of invasive clear cell carcinoma exhibiting a desmoplastic reaction or a diffuse fibrous stroma, but lacking typical adenofibromatous areas, were not included in this study. The benign and low malignant potential tumors showed no clinical evidence of aggressive behavior, whereas those associated with invasive clear cell carcinoma often did. Although there have been no recurrences in our small group of patients with tumors of low malignant potential, the histologic similarity of the epithelium in these tumors to that seen in invasive carcinomas justifies such a categorization. Further studies of larger series using the proposed classification should yield more information concerning the biologic behavior of these types of clear cell adenofibromatous tumors.