A large upper abdominal mass in an adolescent with high Ca 19.9: a case report.

Mucinous cystic neoplasms of the liver are uncommon cystic lesions of the liver, most commonly seen in women in the fifth decade of life. We present a case of a 16-year-old girl with an incidentally discovered abdominal mass while undergoing a tonsillectomy. Investigation revealed a multiloculated, septated 17 × 17 × 11 cm cystic lesion arising from the left lobe of the liver, with displacement of the remaining upper abdominal viscera. Serum Ca19.9 was significantly elevated at 2256 U/ml (range 0-37), but other bloods including liver function tests, alphafoetoprotein and carcinoembryonic antigen were within normal limits. We proceeded to open formal left hemi-hepatectomy. Histology was consistent with a diagnosis of mucinous cystic neoplasm with low-grade intra-epithelial neoplasia.