Benign lesions of the liver are very common findings, usually randomly discovered, especially during examinations for other indications. The frequent use of imaging modalities may be responsible for the statistical increase in the incidence of these findings.

In this publication, we present the cases of 2 female patients with benign liver lesions, the occurrence of which is considered rare, and only a few dozen cases have been described worldwide. In both cases, clinical symptoms, diagnostic approach, and surgical treatment are presented.

Due to increasing availability of imaging methods, the occurrence of previously considered rare benign liver lesions increases as well. In many cases, the malignant potential of these findings remains unclear. Decision-making process should include a multidisciplinary board.

Biliary mucinous cystic neoplasms (BMCNs) are rare and slow-growing lesions that are usually discovered incidentally. They can imitate various other liver tumors. Here, we present a 31-year-old female patient who presented with complaints of abdominal pain, nausea, shortness of breath, and obstructive jaundice. Ultrasound showed a large, lobulated, cystic liver mass. Abdominal computed tomography (CT) scan showed features suggestive of a hydatid cyst or complicated liver cyst. A laparoscopic deroofing was performed and showed a liver cyst involving segments 2, 3, 4A, and 4B. Histopathology showed that the cyst wall was lined by columnar mucin-producing epithelium with multifocal areas of ovarian-like stroma, and the diagnosis of biliary mucinous cystic neoplasms was made. A one-year, follow-up radiological examination did not show any recurrence. BMCNs are quite rare. The nonspecific nature of the symptoms and radiological characteristics makes the diagnosis of BMCN challenging. Imaging modalities can aid in the diagnosis, but pathological examination is essential in confirming a definite diagnosis.

BACKGROUND Mucinous cystic neoplasm (MCN) of the liver is a rare hepatic neoplasm: a cystic, mucus-producing tumor. Histopathologic examination reveals ovarian-like stroma. The origin of MCN of the liver is still unknown, although ectopic ovarian-like stroma in the liver has been suggested as a possibility. We document a thought-provoking case of MCN of the liver, and intratumoral fatty tissue may support the opinion that ectopic ovarian-like stroma in the liver is a possible origin for both MCN and ovarian teratoma. CASE REPORT An expansive 10.5-cm cystic tumor was incidentally detected in a 71-year-old woman. Imaging studies revealed that the tumor was multiloculated, with cyst contents comprising mucus, muddy-looking fluid (inspissated bile), and hematoma. Imaging studies revealed fatty tissue and calcifications in the cyst walls. The diagnosis of MCN of the liver was made, although MCNs have never been reported to include fatty tissue. Extended left lobectomy was performed, and the tumor was curatively removed without any rupture. A multilocular cyst, mucus, calcifications, and fatty tissue were clearly observed on gross inspection. Histopathological examination revealed ovarian-like stroma. Evidence of malignancy was not detected. Her postoperative course was uneventful. To the best of our knowledge, our patient is the first case of MCN of the liver with intratumoral fatty tissue. This case may support the hypothesis that MCN originates from ectopic ovarian-like stroma in the liver. CONCLUSIONS We documented a thought-provoking case of MCN of the liver in detail, and this MCN accompanied with fatty tissue might originate from ectopic ovarian-like stroma.