Mucinous cystic neoplasm or non-parasitic liver cyst? - A challenging diagnosis.

BACKGROUND/AIMS: Mucinous cystic neoplasms (MCN) are rare liver lesions. Radiological features include internal septa or septal thickening. Imaging often fails in the differential diagnosis to non-parasitic liver cysts (NPLC), resulting in inadequate surgery. The aim of the study was to evaluate if both lesions could be differentiated pre-operatively. METHODOLOGY: Retrospective study with literature review. RESULTS: Twenty-six patients (22 female, 68±12 years) underwent laparoscopic deroofing for NPLC. Histo-pathological specimens showed 2 MCN (both female) with recurrence rates of 4% (NPLC) and 100% (MCN), and a time-to-recurrence of 3 months. In both cases no radiological features of MCN were seen pre-operatively. Follow-up time was 7 and 12 years with emergence of radiological features of MCN in one case. PubMed search showed 137 hits for "MCN" and 540 hits for "mucinous cystadenoma" and "liver"; 207 studies were reviewed: one prospective, 13 non-systematic reviews, 57 retrospective, 120 case reports and 16 expert opinions. The largest MCN-series included 44 subjects. CONCLUSIONS: If MCN shows no characteristic radiological features, thus mimicking NPLC, pre-operative radiological differentiation is impossible. During long time course characteristic radiological morphology of MCN could appear. Early recurrence of a supposed NPLC is suspicious for MCN. Due to the literature review pre-operative imaging is inaccurate for the differential diagnosis and complete surgical excision of MCN is crucial.