Synchronous Ovarian and Appendiceal Mucinous Neoplasms in the Absence of Pseudomyxoma Peritonei Ovarian Cancer and Us OVARIAN CANCER and US Ovarian Cancer and Us

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Tuesday, November 22, 2016

Synchronous Ovarian and Appendiceal Mucinous Neoplasms in the Absence of Pseudomyxoma Peritonei
What is Pseudomyxoma Peritonei (“PMP”)?
The term Pseudomyxoma Peritonei has been and still is used to mean a number of different things. This has created much confusion for patients and physicians. Efforts are underway to better define PMP in the medical literature so that there is a better understanding of the term and communication between physicians and patients. Generally speaking, PMP is a rare condition characterized by the presence of mucin in the abdominal cavity. A number of types of tumors can cause PMP, but the most common cause is appendix cancer – including low grade mucinous neoplasms of the appendix.


Synchronous (existing or occurring at the same time) ovarian/appendiceal mucinous neoplasms sometimes occur in the absence of clinical pseudomyxoma peritonei (PMP), which raises a question about whether the 2 tumors could be independent.


We identified 11 cases of synchronous ovarian/appendiceal mucinous neoplasms without PMP and subclassified them into groups 1 and 2 based on the presence or absence of microscopic peritoneal/ovarian surface mucin deposits. A 7-marker panel (CK7, CK20, CDX2, PAX8, MUC1, MUC2, and MUC5AC) immunohistochemistry was performed on both tumors.


Between the 2 groups, there were no significant differences in age, laterality, size, and histology of ovarian/appendiceal tumors. In group 1, 2 of 4 cases developed PMP later, and both had ovarian surface and contralateral ovarian involvement and appendiceal perforation with microscopic mucin deposits on the peritoneum. No patients in group 2 developed PMP. All group 1 cases showed a high degree of concordance of immunoprofile between the synchronous tumors, with an identical expression of appendiceal pattern in greater than 90% of the markers. In group 2, only 1 of 7 cases showed concordance in all markers.


If peritoneal mucin deposits present, even microscopic and acellular, the synchronous tumors are most likely of a single appendiceal origin. Otherwise, they are more heterogeneous, and some may be truly dual primaries.


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