The mucinous cystadenoma (MCN) is a cystic lesion, mucin-producing, almost exclusively found in women, in a ratio of 20:1. The peak incidence is in the 5th decade of life.
The cyst is preferentially located in the body and tail of the pancreas. The main characteristic, in addition to the thick content, rich in mucin, is the ovarian stroma found in the lesion, with receptors for estrogens and progestogens. In the presence of female hormones, the lesion tends to grow in size. In addition, it is a lesion that does not communicate with the pancreatic duct, differentiating them from IPMNs.
The cyst epithelium is composed of columnar cells, mucin-producing. There is a risk of malignant transformation that varies in studies from 0-34%, however there are still no faithful markers that predict the risk of the lesion becoming malignant. What exists are image characteristics that can signal malignant transformation:
- lesions > 3 cm
- presence of mural nodules
- dilation of the main pancreatic duct (> 6mm)
- peripheral calcifications
Diagnosis
The diagnosis of MCNs can be given with a good imaging exam, such as a tomography or magnetic resonance imaging. However, if there is diagnostic doubt, there is the possibility of fine needle aspiration (FNA) via Echoendoscopy. In this case it is important to request biochemical markers such as: amylase (tends to be low), CEA (in mucinous lesions CEA is usually > 190 ng/ml, with an accuracy of 79%) and glucose (usually low in mucinous cysts < 66 mg/dl). When combined, the dosage of CEA and intracyst glucose has an accuracy of 93% for the diagnosis of mucinous lesions.
In doubt of malignant transformation, cytology of the cyst is requested, although the sensitivity is low for the evaluation of dysplasia (about 58%), although the specificity is 96%.
Treatment
MCNs that do not have high risk stigmas for malignancy can be followed with imaging exams (in the first year, an exam every 6 months, and after this period, an annual exam), although it is not possible to exclude the possibility of neoplasia without surgical resection.
When opting to follow up with images, we can delay the treatment of a resectable lesion. Therefore, this decision should take into account the risk of the patient evolving with pancreatic malignancy, as well as his age, life expectancy and other risk factors, such as obesity and smoking. In addition, another alarm sign is recent onset diabetes.
As MCNs are lesions that affect the body and tail of the pancreas (preferably) the resection of this portion of the pancreas tends to be less morbid to the patient. In addition, it is possible to perform the enucleation of the lesion, without necessarily requiring pancreatectomy.
Still as therapeutic alternatives we have the ablation of the lesion with ethanol or paclitaxel, or even radiofrequency ablation. However, these procedures have many adverse effects, and are proposed for patients not candidates for surgery. More studies are needed to indicate ablation as a routine procedure.
Prognosis
The prognosis of the patient who had the MCN resected before malignant transformation is very good, with survival around 100% in 5 years. Patients operated with invasive MCNs, have about 60% survival in 5 years. Lesions < 4 cm without high risk stigmas, have malignancy rates of < 0.05%
See also our article on Serous Cystadenoma of the Pancreas by clicking this link
Bibliography
- Lopes CV. Cyst fluid glucose: An alternative to carcinoembryonic antigen for pancreatic mucinous cysts. World J Gastroenterol 2019 May 21; 25(19): 2271-2278
- Nilsson, LN et al. Nature and management of pancreatic mucinous cystic neoplasm (MCN): A systematic review of the literature. Pancreatology 2016. 1-9.
- Elta, GH et al. ACG Clinical Guideline: Diagnosis and Management of Pancreatic Cysts. Am J Gastroenterol 2018; 113:464–4
- The European Study Group on Cystic Tumours of the Pancreas. European evidence-based guidelines on pancreatic cystic neoplasms. Gut 2018;67:789–804
How to cite this file
Marzinotto M., MUCINOUS CYSTADENOMA (MCN). Gastropedia, 2022. Available at: https://gastropedia/gastroenterology/pancreas/mucinous-cystadenoma-mcn
Medica responsável pelo Grupo de Pâncreas da Disciplina de Gastroenterologia Clínica do HCFMUSP
