Mucin-producing hepatic cystic neoplasms: an uncommon but challenging disease often misdiagnosed and mismanaged.

Background: Mucin-producing hepatic cystic neoplasms (MHCN) are uncommon and potentially malignant.Methods: Nine MHCN were encountered in our centre for over 32 years. Patients' clinical, biological, radiological and pathological features were reviewed. Lesions were classified into Mucinous Cystic Neoplasms (MCN) and Intraductal Papillary Neoplasms of the Bile duct (IPNB) (WHO 2010 classification).Results: Five MCN and 4 IPNB were reviewed. Serum and intracystic tumour markers were insufficient to diagnose malignancy. Complications were encountered in five out of nine patients (56%), mean symptom duration was 26 months (range: 1-132). Three patients were mismanaged pre-referral. Radiological features enabled preoperative diagnosis in eight out of nine patients (89%). Greater tumour size, unilocular lesion and mural nodularity indicated malignancy. Radical tumour excision was achieved in eight patients. One IPNB patient was misdiagnosed and underwent unroofing. For 103 months median follow-up, five out of six patients with benign tumours were alive and disease-free, whereas the misdiagnosed IPNB recurred with fatal malignant transformation seven years later. Among the three patients with malignancies (median follow-up: 77 months), two IPNB died, one from cancer recurrence and one from unrelated causes, whereas the malignant MCN was alive and disease-free.Conclusions: Appropriate MHCN diagnosis is crucial, yet it is often misdiagnosed and mismanaged. The prognosis after complete excision is favourable.