Fine needle aspiration cytology of an ovarian luteinized follicular cyst mimicking a granulosa cell tumor. A case report

BACKGROUND: Fine needle aspiration is a valuable tool in the diagnosis of ovarian cysts, especially in the young and when a nonneoplastic cyst is suspected. High cellularity, epitheliallike clusters and cellular atypia in aspirates from functional cysts are known features that may lead to an erroneous diagnosis of malignancy. Granulosa cells in ovarian cystic fluids may originate in follicular cysts or cystic granulosa cell tumors. In luteinized follicular cysts the cells usually have ample cytoplasm and tend to form clusters. This report draws attention to a case where abundant, dispersed cells lacking cytoplasm led to the incorrect diagnosis of a granulosa cell tumor. CASE: In an ovarian cystic aspirate from a 34-year-old woman, the fluid was highly cellular, with a striking predominance of cells interpreted as granulosa cells. Granulosa cells are often found in aspirates from functional cysts, but striking cellularity, prominent nuclear grooves and lack of luteinization made us consider a granulosa cell tumor rather than a follicle-derived cyst. Surgery was performed, and histology revealed a benign serous cystadenoma but also numerous maturing follicles and follicular cysts with thick layers of granulosa cells. The aspirate obviously did not represent the cystadenoma but one of the prominent follicular cysts. CONCLUSION: An understanding of the cytologic features of functional ovarian cysts, including the pitfalls, is necessary to avoid a false diagnoses of a neoplastic lesion. For a correct interpretation of the cytologic findings, close communication with the clinician and with the radiologist performing the aspiration is of vital importance.