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Well-differentiated papillary mesothelioma in the pelvic cavity. A case report
Tomoko Haba1, Kenichi Wakasa, Masaomi Sasaki
1Department of Pathology, Osaka City University Hospital, 1-5-7, Asahi-machi, Abeno-ku, Osaka City, Osaka, 545-8586, Japan.
Background:
Well-differentiated papillary mesothelioma (WDPM) is considered to be a distinct subtype of peritoneal mesothelioma. It occurs in the peritoneum, is most commonly seen in young women and is found incidentally at laparotomy for other indications. Clinically, WDPM is considered to be benign or to have low malignancy potential.
Case:
A 48-year-old female with no history of asbestos exposure presented with hypermenorrhea. An operation was performed for adenomyosis, and six papillary nodules, 2 cm or less, were found in the serosa of the pelvic cavity. Peritoneal lavage fluid and imprint material from the tumor were obtained for cytologic examination. The cytologic specimens showed many scattered cells and sheetlike clusters and some papillary clusters. These cells had abundant, polygonal, cyanophilic cytoplasm; clearly outlined borders; and slitlike intercellular spaces. The cell arrangement was orderly. The nuclei were uniform in size, with a single centrally located nucleolus, and there were no binucleated forms or mitosis. There was no increase in chromatin. On the luminal surface of the cells, a brush border was observed.
Conclusion:
It is important to differentiate WDPM from diffuse malignant mesothelioma or other peritoneal malignant tumors to avoid treating them as malignant tumors.
Insights
Well-differentiated papillary mesothelioma (WDPM) is a rare peritoneal tumor often found incidentally. Accurate cytologic differentiation from malignant mesothelioma is crucial for appropriate patient management.
Area of Science:
- Oncology
- Cytopathology
Background:
- Well-differentiated papillary mesothelioma (WDPM) is a distinct subtype of peritoneal mesothelioma.
- Typically observed in young women, WDPM is often incidentally discovered during surgery for other conditions.
- Clinically, WDPM is generally considered benign or of low malignant potential.
Observation:
- A 48-year-old female presented with hypermenorrhea and underwent surgery for adenomyosis.
- Six small papillary nodules (<2 cm) were identified on the pelvic serosa.
- Cytologic examination of peritoneal lavage and tumor imprints was performed.
Findings:
- Cytologic specimens revealed scattered cells and clusters with abundant cytoplasm, distinct borders, and slit-like intercellular spaces.
- Cells exhibited uniform nuclei with a single nucleolus, lacking binucleation or mitotic activity.
- A brush border was noted on the luminal cell surfaces, characteristic of mesothelial origin.
Implications:
- Accurate cytologic diagnosis is essential to distinguish WDPM from diffuse malignant mesothelioma.
- Misdiagnosis can lead to unnecessary aggressive treatment for a potentially benign condition.
- This case highlights key cytologic features for identifying WDPM.
