Mucinous nonneoplastic cyst of the pancreas: CT and MRI appearances

Simple mucinous cyst: another potential cancer precursor in the pancreas? Case report with molecular characterization and systematic review of the literature

Cystic lesions of the pancreas may range from benign to precursors of pancreatic cancer. Simple mucinous cyst (SMC) is larger than 1 cm, has a gastric-type flat mucinous lining, and minimal atypia without ovarian-type stroma. We report a new case of pancreatic SMC, coupling a systematic review of the English literature mainly focused on their clinic-pathological features. We reviewed 103 cases of SMC in adults (73 women), averaging 57 (range, 26–70) years. The SMCs were located in the body-tail region of the pancreas in 60 (58%) cases, presenting as single cystic lesions in 94% of cases; 43% of patients were asymptomatic. A preoperative fine-needle aspiration of the cyst fluid detected amylase and carcinoembryonic antigen positivity in 71% and 76% of cases, respectively. Patients underwent surgery mostly for suspected malignancy; in 83% of cases, a standard pancreatic resection was performed. Mean SMC size was 4.9 (range, 1.5–12.0) cm. Mucins MUC5AC and MUC6 resulted positive in 77% and 81% of cases performed, respectively, whereas MUC2 was negative in all but one patient. The SMC from our institution was characterized by a KRAS somatic mutation. The diagnosis of SMC should be considered when a solitary pancreatic cyst larger than 1 cm is detected in asymptomatic patients. To establish a correct diagnosis, an extensive histologic/immunohistochemical analysis is essential. The presence of a KRAS mutation highlights that SMC may represent another potential pancreatic cancer precursor.

Laparoscopic Resection and Pre-Operative Imaging of Primary Retroperitoneal Mucinous Neoplasms: A Retrospective Case Series

Purpose

The purpose of this paper is to present the clinicopathological features of primary retroperitoneal mucinous neoplasms (PRMNs), to evaluate the diagnostic role of pre-operative radiological examinations, and to determine the feasibility of total resection using the laparoscopic approach.

Methods

We retrospectively analysed the clinicopathological and radiological features of 10 PRMN cases who underwent surgical resection from January 2000 to December 2019.

Results

Ten PRMN cases were evaluated in this study, including 1 malignant case, 4 borderline cases, and 5 benign cases. The most common primary complaints were pain (60%) and palpable mass (60%). Of the 8 cases with pre-operative CT results, 75% of the borderline or malignant cysts and none of the benign cysts were large in size (size>11.6 cm). Half of the non-benign masses and none of the benign ones were lobulated. Thick wall (≥3 mm) and irregular wall were found in 25% and 50% of the non-benign cases, respectively. Wall enhancement was detected in 75% of the non-benign cases and 25% of the benign cases. Enhanced mural nodules were identified in 50% of the non-benign patients. Septa were found in 25% of the non-benign cases. Complete dissection of the tumour without rupture or post-operative complications was achieved laparoscopically in 90% of the cases. All patients were alive with no recurrence at the last follow-up at an average of 28.1±26.6 months.

Conclusion

Larger size and lobulation of the cyst, presence and contrast enhancement of thick and irregular cyst walls, mural nodules, and internal septa may be imaging features suggestive of malignancy. Complete resection of PRMN through the laparoscopic approach is feasible in experienced institutions.

Imaging findings for mucinous tumors of the abdomen and pelvis

This article aims to describe the imaging findings for mucinous tumors of the abdomen and pelvis, which have a similar appearance on imaging tests regardless of the organ in which they develop. Due to the high water content of mucus, the appearance of these tumors is generally similar to that of water on ultrasonography, computed tomography, and magnetic resonance imaging. Another common feature of mucin-producing tumors is that calcifications are often present. The rupture of these lesions and accumulation of mucinous material in the peritoneal cavity gives rise to pseudomyxoma peritonei. It is important to identify mucinous tumors because they have a different prognosis and clinical course than non-mucinous tumors and require different management. Depending on their anatomic location and their imaging characteristics, the treatment approach varies from follow-up to radical surgery together with chemotherapy or radiotherapy or both.