We felt these most likely represented extrauterine disease but the sparse cellularity precluded further classification. The pleural and ascitic fluid were abundantly cellular and shared cytomorphologic features with the Pap smear. A diagnosis of adenocarcinoma was rendered on each fluid. The most common source for adenocarcinoma from outside the cervix or endometrium is the ovary. Ovarian cancers on cytologic smears will have clean backgrounds, and the cells are usually larger than the typical endocervical or endometrial adenocarcinomas.
Neoplastic clusters are tight, three-dimensional and generally have prominent macronucleoli.
Psammoma bodies can be identified but are not pathognomonic of ovarian neoplasia. Fallopian tube adenocarcinomas are cytomorphologically similar in appearance to serous ovarian tumors and the distinction can not be made on cytologic grounds alone. It can be difficult to differentiate between adenocarcinoma of endocervical or endometrial origin on cervical smears. Endocervical adenocarcinomas commonly show a diathesis, abundant cellularity and architectural features of columnar origin. There are crowded, two dimensional sheets of cells with rosette-like formation in the groups.