Predictors of malignant potential of cystic lesions of the pancreas

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Abstract

Background

Cystic lesions of the pancreas (CLP) are a diagnostic dilemma, the correct characterisation of which determines surgical management.

Methods

From 1995 to 2005, radiology and pathology records were reviewed for the presence of CLP. CLP were divided into three groups; Group 1: Benign, Group 2: Pre-malignant, and Group 3: Malignant.

Results

Seventy-nine of 121 patients were included [Group 1: n = 46, Group 2: n = 10, Group 3: n = 23], with a median age at diagnosis of 68 (31–92) years. The median follow-up period was 24 (14–84) months. On univariate analysis, female gender (p = 0.04), jaundice (p < 0.01), raised serum ALT concentration (p = 0.03), cyst size (≥2.5 cm) (p < 0.01), and biliary duct dilatation (p < 0.01) were associated with malignant potential. Benign cysts were more likely to present incidentally (p < 0.01). On multi-variate analysis, cyst size (≥2.5 cm) was an independent predictor of malignant potential. Sub-group analysis revealed that cysts < 2.5 cm in the head of the pancreas with evidence of biliary obstruction (either abnormal liver function; raised ALT [p = 0.01], ALP [p = 0.01], total bilirubin [p = 0.02], and/or biliary duct dilatation [p < 0.01]) were associated with malignant potential.

Conclusion

Cyst size ≥2.5 cm on computer tomography imaging was an independent predictor of pre-malignant and malignant pancreatic cysts. Cyst size and the presence of biliary obstruction predict potentially malignant cysts of the head of the pancreas, which require surgical management.

Introduction

Cystic lesions of the pancreas (CLP) are increasingly being recognized due to more awareness and the widespread use of abdominal cross-sectional imaging.1, 2, 3 Although approximately 90% of cystic masses are pancreatitis-associated pseudocysts, the remaining lesions are neoplasms of varying histology.1, 4 Recent reviews have revealed that CLP are very variable in their morphology, clinical behaviour and pathogenesis.5, 6 Kosmahl et al. have recently proposed an extensive histopathological classification of pancreatic cystic neoplasms and tumour-like lesions with cystic features.7 This classification includes neoplastic and non-neoplastic lesions of epithelial and non-epithelial origin. The main differential diagnoses are benign lesions such as pancreatitis-associated pseudocysts and inflammatory cysts, neoplasms with malignant potential such as mucinous neoplasms and solid pseudo-papillary neoplasms, and malignancy such as intraductal papillary-mucinous carcinoma and invasive ductal adenocarcinoma.

In the clinical setting, it is crucial to differentiate between a benign and malignant CLP as the management of these conditions is entirely different. Due to the malignant potential of certain cystic neoplasms and the potential cure following surgery, current recommendations suggest that patients with CLP should undergo curative resection if feasible.8, 9, 10 Failure to accurately characterize CLP can lead to inappropriate treatment.11 Misdiagnosing cystic neoplasms as pancreatic pseudocysts is not uncommon, and in one series this occurred in 33% of cases.1 Therefore, the ability to differentiate benign, pre-malignant and malignant lesions based on clinical presentation, biochemistry, and/or radiological imaging is important.

The aim of the current study was to identify predictors of neoplastic potential in CLP at the time of presentation, to determine which patients should undergo further investigation and/or surgery.

Section snippets

Demographic data

Patients diagnosed with CLP at the Leeds Teaching Hospitals (LTH) NHS Trust during the 11-year period, from January 1995 to December 2005, were identified using the hospital's pathology database and radiology computer coding system (Radiology Management System - RMS). The RMS search identified patients with a cystic lesion of the pancreas stated in radiology reports, which included abdominal ultrasonography (USS), computer tomography (CT), magnetic resonance imaging of the pancreas (MRI),

Demographic data

During the study period, 121 patients with CLP were identified, of which 79 patients were included. Thirty-one patients with chronic pancreatitis, eight patients with von-Hippel Lindau disease and three patients with a recent history of acute pancreatitis were excluded from the study. There were 27 men and 52 women, and the median age at diagnosis was 68 years (range: 31–92 years).

Forty-eight patients presented with abdominal pain, 17 patients with jaundice, and 27 patients with weight loss.

Discussion

The management of CLP is still highly debatable and largely depends on accurate characterisation of the underlying pathology. Although an aggressive resectional approach is recommended by some authors,10 many clinicians still question this policy in light of an increasing number of CLP being identified incidentally.12, 13

Conclusion

In conclusion, cyst size is an independent predictor of malignant potential of CLP. CLP with malignant characteristics are more likely to present with symptoms, such as jaundice. For cystic lesions less than 2.5 cm in size in the head of the pancreas, abnormal liver function tests and/or the presence of biliary duct dilatation is associated with malignant potential.

Conflict of interest

The authors have no conflict of interest.

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