International consensus guidelines for management of intraductal papillary mucinous neoplasms and mucinous cystic neoplasms of the pancreas

Pancreatic serous oligocystic adenomas: clinicopathologic features and a comparison with serous microcystic adenomas and mucinous cystic neoplasms

INTRODUCTION

The preoperative distinction between serous cystic neoplasms (SCNs) and mucinous cystic neoplasms (MCNs) is essential, as all MCNs are considered malignant or potentially malignant and should be surgically resected, whereas SCNs are almost always benign. However, the radiologic distinction between SCNs and MCNs is frequently difficult especially with serous oligocystic adenoma (SOA), a morphologic variant of SCN, as both SOA and MCN appear on cross-sectional imaging as a solitary macrocystic lesion in the pancreas. We reviewed all SOAs managed at our institution to determine if any clinicopathologic features would prove useful for establishing a preoperative diagnosis.

METHODS

Over a 15-year period, 64 patients with a pathologically confirmed diagnosis of a pancreatic cystadenoma or cystadenocarcinoma treated at Singapore General Hospital were retrospectively reviewed. There were 27 MCNs and 37 SCNs including 12 SOAs. In addition, 40 cases of SOA previously reported in the literature were reviewed and analyzed together with the 12 patients, making this a series of 52 SOAs.

RESULTS

In our experience, SOAs comprised 32.4% of the SCNs, and females predominated (7/12). The median age of the patients was 42.5 years (range 22-74 years), and only 4 of the 12 patients were symptomatic. Most of the cysts were located in the body or tail of the pancreas (9/12), and the median cyst size was 52.5 mm (range 10-190 mm). When the clinicopathologic features of SOAs and serous microcystic adenomas (SMAs) were compared, there was no difference between the patients with SOAs and SMAs in terms of age, sex, presence of symptoms, cyst size, or site of the lesion. However, SOAs occurred in the women less frequently (67.3% vs. 96.3%, P=0.004), were smaller [40 mm (range 10-190 mm) vs. 95 mm (range 25-180 mm), P<0.001], and occurred more commonly in the head of the pancreas [25 (48.1%) vs. 2(7.4%)] compared to MCNs. None of the SOAs were frankly malignant compared to the 29.6% of MCNs that were.

CONCLUSIONS

SOAs and SMAs have similar clinicopathologic features. On the other hand, SOAs differ from MCNs by their relatively higher male/female ratio, higher frequency of tumors occurring in the head of the pancreas, and smaller cyst size. Knowledge of these distinguishing clinical features when used in combination with other diagnostic modalities such as endoscopic ultrasonography/fine-needle aspiration will enable clinicians to better differentiate these two pathologic entities preoperatively.

Intraductal papillary-mucinous neoplasms and mucinous cystic neoplasms of the pancreas differentiated by ovarian-type stroma

BACKGROUND

Intraductal papillary-mucinous neoplasms (IPMN) and mucinous cystic neoplasms (MCN) of the pancreas have similar clinicopathologic findings. This study was intended to clarify clinicopathologic characteristics in IPMNs and MCNs differentiated by ovarian-type stroma.

METHODS

Medical records for 77 patients with pancreatic cystic neoplasms with mucin secretion were reviewed. Patients were divided into IPMN (n = 70) or MCN (n = 7) according to the presence of ovarian-type stroma, and clinicopathologic parameters were compared between groups.

RESULTS

IPMNs consisted of 32 adenomas, 12 borderline neoplasms, 13 adenocarcinomas in situ, and 13 invasive adenocarcinomas; MCNs included 6 adenomas and 1 invasive adenocarcinoma. The mean age of IPMN patients (66 years) was significantly older than that of MCN patients (55 years). The male:female ratio in IPMN (53/17) was significantly greater (P < .001) than in MCN (0/7). The location of the pancreatic mass differed, with 76% 0f IPMNs occurring in the head, while 86% of MCNs occurred in the body or tail. Mass mean size was significantly smaller (28 mm vs 78 mm, P < .001), and mean diameter of the main pancreatic duct was larger (6.8 mm vs 3.1 mm, P < .001) in IPMN than in MCN. Patulous papilla was present in 44% (31/70) of IPMNs, but none was present in MCNs. Communication between the cyst and main pancreatic duct was more frequent in IPMNs (67/70) than in MCNs (1/7). Overall 5-year survival rates were 84% (IPMN) and 100% (MCN).

CONCLUSIONS

Clinicopathologic differences between IPMN and MCN are much clearer when differentiated by presence of ovarian-type stroma. Favorable prognosis for both neoplasms is offered by complete resection.

Cystic pancreatic lesions: a simple imaging-based classification system for guiding management

Cystic lesions of the pancreas are increasingly being recognized due to the widespread use of cross-sectional imaging. The initial evaluation of a pancreatic cyst should be directed toward exclusion of a pseudocyst. Patients with pseudocysts generally have a history of acute or chronic pancreatitis, whereas those with cystic tumors most often lack such a history. Several types of cystic lesions are encountered in the pancreas. Because of morphologic overlap at imaging, accurate characterization of these lesions can be difficult. Computed tomography and magnetic resonance imaging are excellent modalities for both initial detection and characterization of cystic pancreatic lesions. An imaging classification system for these lesions has been proposed that is based on the morphologic features of the lesion. This system can be helpful in characterizing lesions, narrowing the differential diagnosis, and making decisions regarding the treatment of affected patients. Endoscopic ultrasonography-guided aspiration and biopsy is useful in cases that are indeterminate at cross-sectional imaging or that require observation.

Intraductal papillary mucinous neoplasms of the pancreas

The introduction of the exocrine pancreatic classification by the World Health Organization and improvements in pancreatic imaging have led to an improved understanding of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. As a result, IPMNs of the pancreas are increasingly being recognized as a separate disease entity. IPMNs are characterized by the cystic dilatation of the pancreatic duct and its branches, with papillary projections. There are three histological subtypes of IPMNs: main duct, branch duct, and mixed. The degree of atypia ranges from adenoma to frank invasive carcinoma. The lymph nodes are involved considerably less frequently than they are in pancreatic adenocarcinoma. Most patients are symptomatic at diagnosis and require a diagnostic workup similar to that for patients with pancreatic adenocarcinoma. Although some investigators continue to advocate total pancreatectomy, the evidence in support of this is decreasing. Partial pancreatectomy remains the treatment option. Intraoperative assessment of the resection surgical margins is an important component of surgical resection. Additionally, controversy also exists regarding the nature of the follow-up and the need for adjuvant chemoradiation therapy in the patient. Unlike ductal adenocarcinomas, IPMNs follow a relatively indolent course; the 5-year survival rate in patients with invasive IPMNs is 57%. A mural nodule and a main pancreatic duct diameter greater than 5 mm have been found to be predictors of malignancy.

Pancreatic cancer

Pancreatic cancer remains a major unsolved health problem, with conventional cancer treatments having little impact on disease course. Almost all patients who have pancreatic cancer develop metastases and die. The main risk factors are smoking, age, and some genetic disorders, although the primary causes are poorly understood. Advances in molecular biology have, however, greatly improved understanding of the pathogenesis of pancreatic cancer. Many patients have mutations of the K-ras oncogene, and various tumour-suppressor genes are also inactivated. Growth factors also play an important part. However, disease prognosis is extremely poor. Around 15-20% of patients have resectable disease, but only around 20% of these survive to 5 years. For locally advanced, unresectable, and metastatic disease, treatment is palliative, although fluorouracil chemoradiation for locally advanced and gemcitabine chemotherapy for metastatic disease can provide palliative benefits. Despite pancreatic cancer's resistance to currently available treatments, new methods are being investigated. Preoperative chemoradiation is being advocated, with seemingly sound reasoning, and a wider role for gemcitabine is being explored. However, new therapeutic strategies based on the molecular biology of pancreatic cancer seem to hold the greatest promise.