Differentiating a large abdominal cystic lymphangioma from multicystic mesothelioma: report of a case.

We report a case of retroperitoneal cystic lymphangioma in a 30-year-old woman who presented with abdominal distention and pain. Imaging studies revealed a large, thin-walled multicystic mass occupying the whole abdomen. Based on a preoperative diagnosis of multicystic mesothelioma, we performed laparotomy, which revealed a tumor arising from the gastropancreatic ligament in the posterior wall of the omental bursa. We resected the tumor completely, without the adjacent viscera. The final pathological diagnosis was cystic lymphangioma, based on the immunohistochemical findings of positive CD31 and CD34 expression, the presence of smooth muscle confirmed by smooth muscle antigen and desmin, and negative calretinin, WT-1 and cytokeratins 5/6 expression. Multicystic mesotheliomas and cystic lymphangiomas are so similar in morphology that immunohistochemical staining should be fully utilized to differentiate them.