Endocrine cell micronests in an ovarian mucinous cystadenofibroma: a mimic of microinvasion.

An ovarian mucinous cystadenofibroma with peculiar neuroendocrine cell micronests is described in a 59-year-old Japanese woman. Aggregates of epithelial cells resembling microinvasive carcinoma cells were scattered throughout the adenofibromatous area. These micronests were composed of small uniform cells with argentaffin and argyrophil granules. Numerous small cells with neuroendocrine granules were also seen within mucinous glands. This is the first report of neuroendocrine micronests in an ovarian neoplasm, a finding that should be distinguished from microinvasion.