Cytology of pseudomyxoma peritonei.

The cytology of five cases of pseudomyxoma peritonei is described. It is characterized by large masses of mucinous material, some of which is wrapped up in a network of elongated fibroblast-like cells. Irregular clusters of flat branching vimentin-positive fibroblast-like cells may be found as the disease progresses. Goblet or tumour cells were not found in the cytology preparations, although they were seen in the histological sections of the one case which was biopsied. The appendiceal origin of pseudomyxoma peritonei could not be traced in three of four male patients, and the cause of the disease remained undetermined. Autopsy of the fourth case demonstrated a complete replacement of the appendix by mucus.