Australian Society of CytologyCase of the Month
January 2004 - Answer and Discussion
Pseudomyxoma Peritoneii with an isolated focus suggestive of a mucinous adenocarcinoma.
Discussion
The peritoneal fluid was viscous,mucoid and difficult to smear resulting in thick preparations.
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The smears showed a thick background of mucoid material with scattered, scanty inflammatory and mesothelial cells.
The biopsies showed numerous papillae distended by abundant mucinous material and lined by reactive mesothelial cells. The features are those of Pseudomyxoma Peritoneii.
In addition there is a tiny focus of colonic-type epithelial cell in one area suggestive of a mucinous adenocarcinoma.
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Pseudomyxoma Peritoneii is the widespread involvement of the peritoneal cavity by mucin, the source of which may be a mucinous borderline tumour or a well-differentiated mucinous adenocarcinoma of ovary or appendix.
These cystic tumours may rupture, seeding tumour cells throughout the peritoneum.
The malignant cells continue to proliferate and produce abundant amounts of PAS positive mucin which slowly accumulates, resulting in a large peritoneal effusion.
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The viscosity of the mucin can make aspiration difficult. Smears often have poor cellularity making it necessary to prepare multiple smears or repeat the aspiration procedure in order to obtain adequate diagnostic material.
Careful screening is required in cases of Pseudomyxoma Peritoneii to identify any abnormalities in the often low numbers of mucin secreting cells present.
This is clearly evident in this case as only a single,tiny focus of malignancy was identified in the biopsy material submitted to the laboratory.
References:
1.Gray W,Diagnostic Cytopathology,Churchill Livingstone 1995
2.Bibbo M,Comprehensive Cytopathology,WB Saunders Company 1991
