Lymphangiomas are rare benign cystic tumors. They originate from developmental failure or inflammation of lymphatics causing obstruction. More than ninety percent of lymphangioma cases are diagnosed within the first two years of life. They are mostly (95%) found in the neck and axillary regions. Intra abdominal lymphangiomas are quite rare, and the most common locations are the retroperitoneum, mesentery, omentum and the mesocolon. Biliary tract or gallbladder cancers are often with regional lymph node metastasis but benign tumors such as lymphangioma should be kept in mind. Lymphangioma co- existing with a solid tumor might cause false over-staging and curative treatment option might be missed for some patients. A rare case of retroduodenal cystic lymphangioma co-existing with gallbladder adenocarcinoma is presented.