MESOTHELIAL INCLUSION CYST IN PATIENT WITH BECKWITH-WEIDEMANN SYNDROME: A RARE CASE REPORT

Objectives: Mesothelial inclusion cysts are rare benign tumors not frequently reported in literature. When reported, they seem to primarily be found in adults. (1–3) One report from 2006 reports an association with Beckwith-Weideman syndrome, but no other reported cases discuss this correlation.(4) We describe a case of a patient with Beckwith-Weideman syndrome who in the setting of an omphalocele repair was found to have hepatic cysts with pathology revealing mesothelial inclusion cysts.

Methods: A 0 day old female born via cesarean section at 34 weeks 6 days with giant omphalocele. Of note, other abnormalities included macrosomia and a sacral dimple. Primary operative repair was performed on first day of life. Findings included a 6 cm fascial defect which was primarily repaired. In addition, multiple hepatic cysts along a narrow tongue of liver that included the gallbladder were noted to be extending off the right lobe protruding through the fascial defect. The patient was managed in the NICU until she tolerating adequate oral intake. Genetic testing subsequently revealed a diagnosis of Beckwith-Weideman syndrome. The pathology report of the hepatic cysts showed mesothelial inclusion cyst with hepatic plate malformation. To our knowledge, this is the second case describing mesothelial inclusion cysts of the liver in a clinical setting of Beckwith-Wiedeman syndrome in English literature.

Results: Mesothelial inclusion cysts represent benign cystic lesions delineated by a single layer of mesothelial cells and have been described in a variety of anatomical locations, typically on the serosal surface of visceral organs.(1) Beckwith-Weideman Syndrome is a genetic disorder characterized by alterations in growth regulatory pathways leading to gigantism, macroglossia, and tumor predisposition. It is also known for increased frequency in abdominal wall defects such as omphalocele and diastasis recti. (5) In this case study, they note the patient had an omphalocele containing an accessory lobe of liver that contained cysts. Pathology showed a thin layer of mesenchymal cells with immunohistochemical (IHC) staining reactive for calretinin, cytokeratin, and D2-40, thus confirming mesothelial origin. (4) Our patient had similar findings on IHC staining reactive for D2-40, calretinin, CK5/6. Prior to the advent of IHC staining, cysts of this origin were difficult to discern as endothelial vs mesothelial. (6)

Conclusion: Mesothelial inclusion cysts are a rare entity, especially in children. We believe the discussed case is only the second described in the literature in a patient with Beckwith-Weideman syndrome.