Ovarian follicular cysts: a potential source of false positive diagnoses in ovarian cytology.

The cytology samples of 22 benign ovarian cysts aspirated during laparoscopy (16) or laparotomy (6) were evaluated for clinicopathologic correlations. Clinically, most patients were evaluated for chronic pelvic pain. The cysts ranged in size from 1 to 5 cm (average 2.4 cm), and were described as having benign appearance. Cytologically, small granulosa cells arranged in clusters or isolated had granular cytoplasm with occasional microvacuoles. The nuclei were round to oval, uniform, and eccentrically placed. They had granular chromatin with chromocenters and one to two micronucleoli. Relative nuclear area averaged 50%. Mitoses were present in all but two cases, ranging from 0 to 38 mitoses per 10 high power fields (average 7.2 mitoses per 10 high power fields). Present in some cases were mesothelial cells and histiocytes. Three cases with follow-up histopathology specimens revealed two follicular cysts and a collapsed cyst without discernible lining. The immature appearance of the granulosa cells, the granular chromatin, and the presence of mitoses often suggested cytologically the possibility of a neoplastic process. Recognition of the cytopathology features, knowledge of the clinical history, and the laparoscopic findings may reassure the pathologist about the benign nature of the cysts.