[1686] Endometrial Cysts within the Liver: A Rare Entity and Its Differential Diagnosis with Mucinous Cystic Neoplasms of the Liver

Maylee Hsu, Benoit Terris, Tsung-Teh Wu, Hock-Liew Eng, Wan-Ting Huang, Matthew Yeh. University of Washington, Seattle, WA; Descartes University, Paris, France; Mayo Clinic, Rochester, MN; Chang-Gung University, Kaohsiung, Taiwan

Background: Endometrial cysts within the liver are rare occurrences, but can present as diagnostic challenges on small biopsies or frozen sections. One diagnostic pitfall is their clinical, histologic, and immunohistochemical features overlapping with mucinous cystic neoplasm (MCN) of the liver, which also has stroma underlying epithelium. We compare these two entities with respect to the clinical and immunohistochemical profiles.
Design: 4 cases of endometrial cysts within the liver were collected. Clinical and image records were reviewed. Immunostains including CK19, CK7, calretinin, SMA, vimentin, inhibin, ER, PR, and CD10 were analyzed. Immunostains (ER, PR, and inhibin) of 6 cases of MCNs of the liver were also analyzed.
Results: The mean ages of the patients with MCNs and endometrial cysts were 46 yrs (range 31-64) and 50 yrs (range 20-73), respectively. 3 of the 4 cases of endometiral cysts were located in the right lobe of liver (mean size: 8 cm). 2 patients presented with abdominal pain and 3 patients had a prior pelvic operation. 3 of the 4 patients had coexisting endometriosis. All 4 cases of endometrial cysts had positive ER, PR, and vimentin staining within both the epithelium and underlying stroma. 3 cases had additional immunostains performed (not available in the 4th case due to tissue exhaustion), which all showed CK19 and CK7 positivity (only in epithelium), CD10 positivity (only in stroma), and inhibin and calretinin negativity (in epithelium and stroma). 1 case had SMA positive stroma. All 6 MCN cases were located in the left lobe of liver (mean size: 11 cm) with positive ER, PR, and inhibin staining only present in the stroma, but not in the overlying epithelium.
Conclusions: Endometrial cysts of the liver can mimic MCNs both clinically and morphologically. Interestingly, most endometrial cysts occur in the right lobe, while all MCN occurred in the left, suggesting their distinct pathogenesis. The key immunohistochemical distinctions are ER and PR positivity in both the epithelium and stromal cells in endometrial cysts, as compared to ER and PR positivity only present within the stromal cells of MCNs. Also the stromal cells are CD10 positive and inhibin negative in cases of endometrial cysts, with the opposite staining pattern in MCNs. Awareness of this distinct staining pattern and the possibility of hepatic endometrial cysts can lead to accurate diagnoses and appropriate treatment modalities.
Category: Liver

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 194, Tuesday Morning


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