Mucinous Cystic Pancreatic Neoplasm - Causes, Features, Diagnosis, and Management

Introduction

The cystic neoplasms of the pancreas are classified as serous cystic pancreatic neoplasms and mucinous cystic pancreatic neoplasms. The mucinous cystic pancreatic neoplasm is present mainly in middle-aged females (more than 40 years). It is often confused with intraductal papillary mucinous neoplasm (IPMN). With histological findings, it is now confirmed that both these lesions show different biologic behavior, pathological features, and prognosis.

What Are the Features of Mucinous Cystic Pancreatic Neoplasm?

• These are less common than serous cystic pancreatic neoplasm and intraductal papillary mucinous neoplasm.

• According to the research studies, all the cases are premalignant.

• Female preference.

• The body and the tail of the pancreas are mostly affected.

• It is filled with mucus or hemorrhagic material.

What Is the Etiology of Mucinous Cystic Pancreatic Neoplasm?

The etiology of mucinous cystic pancreatic neoplasm is not known. Researchers have claimed that the presence of female hormones can be the leading cause as the disease is mainly concentrated in the female population. This rationale is because the ovarian cystic pancreatic neoplasm and mucinous cystic pancreatic neoplasm share the same histological features. The shared features include mucinous-secreting columnar epithelial cells and ovarian stroma. Both pancreatic neoplasms show benign features and rarely spread to involve other organs and lymph nodes. The estrogen receptors of the mucinous cystic pancreatic neoplasm are another factor that supports the hormonal cause of the disease. However, these tumors have the potential to evolve into malignancies and cause cancer.

What Is the Pathophysiology of the Mucinous Cystic Pancreatic Neoplasm?

Mucinous cystic pancreatic neoplasms show two distinct histological features. The first one is the presence of mucin-secreting cells, and the second is the presence of ovarian stoma. These features distinguish it from serous cystic pancreatic neoplasms and papillary mucinous neoplasms. They are mainly benign lesions; however, whenever they invade, the malignant cells can be found beyond the epithelial lining of the cyst. Due to the presence of ovarian stroma, many estrogen receptors were found in these tumors. The invasive tumors are intracapsular (if cancer does not pass through the capsule) and extracapsular (if the tumor extends through the wall into the surrounding pancreatic tissue). The tumor is benign but can potentially convert into a malignant neoplasm. Tumors with nodules and a size larger than 4cm most likely converts into malignant mucinous cystic pancreatic neoplasm. Unlike intraductal papillary mucinous neoplasms, they are not connected to the pancreatic ducts.

What Are the Clinical Features Seen in Mucinous Cystic Pancreatic Neoplasm?

Mucinous cystic pancreatic neoplasms are slow-growing asymptomatic tumors, mostly coincidentally discovered during the scanning process for other lesions. Therefore, patients are usually asymptomatic and present in the clinical setup with the below-mentioned clinical signs.

• Abdominal pain.

• Weight loss and fatigue.

• Increased abdominal mass.

• The sensation of being full (due to compression of the surrounding tissue).

• Obstructive jaundice is not present, as the lesion is mainly seen in the body and tail of the pancreas.

• Nausea, vomiting, and back pain are other symptoms.

How Is a Preoperative Evaluation Done?

Preoperative evaluation is based on clinical features, tumor markers, computed tomography (CT) scan, magnetic resonance imaging (MRI), endoscopic ultrasound (EUS) for cyst fluid, and positron emission tomography (PET). If the tests show high expression of tumor markers CA 19-9 and CEA (carcinoembryonic antigen) value, the lesion is malignant. A transabdominal ultrasound examination is done for cystic neoplasm of the pancreas; however, the accuracy is low. Endoscopic ultrasound examination improves the evaluation and accuracy. It is used to aspirate the cystic contents and perform the biopsy.

What Is the Treatment of Mucinous Cystic Pancreatic Neoplasm?

Surgical resection is the treatment for all premalignant mucinous cystic pancreatic neoplasms. The surgical treatment plan is greatly influenced by the age and risk involved, the size and location of the tumor, and the histological features.

• Left or Distal Pancreatectomy - Removal of the pancreas (all or parts of the pancreas) is the preferred method. Since mucinous cystic adenoma usually occurs at the tail and body of the pancreas, a left or distal pancreatectomy is performed. The main complication of surgery is a pancreatic fistula.

• Middle Pancreatectomy - When the mucinous cystic pancreatic neoplasm occurs at the neck or the body, a middle pancreatectomy is performed. The treatment goal is the endocrine and exocrine function of the pancreas, along with spleen preservation. Postoperative complications are more along with recurrence due to the residues of the neoplasm.

• Enucleation - Enucleation (removal of the entire cystic capsule) is the treatment of choice for lesions that are less than 2 cm in size. It prevents the chances of recurrence. Pancreatic fistula is a postoperative complication.

• Lymphadenopathy - Lymphadenopathy (dissection of lymph nodes) is the treatment of choice in the presence of invasive carcinoma.

• Chemotherapy - Drugs like Gemcitabine are given to the patients. This drug is highly effective in the treatment of lesions. Gemcitabine and Oxaliplatin combination is also being tested to know the efficacy and effectiveness.

• Whipple Procedure - It is also known as a pancreaticoduodenectomy. The Whipple procedure is recommended when the mucinous cystic pancreatic neoplasms are localized in the head of the pancreas. The duodenum is preserved in case the lesion is non-invasive. The most common complication is delayed gastric emptying and pancreatic fistula.

• Conservative Treatment - FNA cytology and imaging techniques are suggested for patients with asymptomatic cystic lesions of the pancreas with a size of less than 3 cm. The cytology and imaging tests are conducted every six months for two years and then annually for the next four years. The interval of the follow-up visit is then increased to six years. Surgery is mandatory when the cyst enlarges or if symptoms appear.

What Is the Prognosis of Mucinous Cystic Pancreatic Neoplasm?

If the mucinous cystic pancreatic neoplasm is non-invasive, the prognosis is good. The patients do not need postoperative follow-up, and according to the research, the chances of recurrence after surgery are negligible. In the case of invasive lesions, the five-year survival rate is better than other pancreatic lesions.

What Is the Differential Diagnosis of Mucinous Cystic Pancreatic Neoplasm?

Other diseases with similar clinical presentations are mentioned below, and various tests should be conducted to conclude with the correct diagnosis.

• Acute pancreatitis.

• Bile duct tumors.

• Gastric cancer.

• Peptic ulcer.

• Chronic pancreatitis.

Conclusion

It is essential to distinguish mucinous cystic pancreatic neoplasm from intraductal cystic papillary mucinous neoplasm. There is no standard management method for mucinous cystic pancreatic neoplasm, and the interprofessional team works together to treat the lesion successfully. There is no specific method to identify the benign mucinous cystic pancreatic neoplasm that can progress into malignancy, so all the lesions should be surgically resected irrespective of their size. Postoperative follow-up and diagnostic imaging are not required.