Large multilocular serous cystadenoma of the pancreatic head

Introduction
Cystic tumours of the pancreas are relatively rare, but they constitute an increasingly important pathology with a challenging differential diagnosis (1). They represent a spectrum of disease ranging mainly from pancreatic pseudocysts, serous cystadenoma, mucinous cystadenoma and cystadenocarcinoma. However the true cystic tumours of the pancreas are considered only the last three ones (2). The behaviour of cystic tumours of the pancreas has been a subject of controversy. It is important to differentiate them from pseudocysts and ductal adenocarcinoma (3). It seems that symptoms and signs among the patients with cystic or solid tumours of the pancreas are quite similar excepting the fact that serous cystadenoma are more likely to be asymptomatic (4). It is considered that serous cystadenoma are more likely to appear in older women (1, 5), being located mainly in the head of the pancreas (2, 5, 6). Preoperative accurate diagnosis is still difficult even nowadays, despite the progresses gained in the field of medical imaging. We choose to present this case in order to highlight the fact that preoperative differential diagnosis of a cystic tumour in the head of the pancreas can be very challenging and large serous cystadenoma can exhibit symptoms like pain and compression to the neighbouring organs. In this case the accurate diagnosis was established by intraoperative exploration and confirmed after histopathological examination.

Case report
An 88-year-old female patient was admitted in our unit for upper abdominal pain. Clinical examination revealed a large upper abdominal mass. The medical history of the patient included: arterial hypertension, chronic ischemic heart disease with recent acute ischemic heart attack. The enhanced abdominal CT-scan described a round upper abdominal mass, heterogeneous, multiseptated, with mild capture of the intravenous contrast substance, with diameters of 9.4/9 cm, with many cystic areas and microcalcifications, located in the area of the pancreatic head (fig.1); the tumour compressed the duodenum and distal common bile duct determining dilatation of the intra and extrahepatic bile ducts (diameter of the common bile duct - 2.9 cm); the tumour also compressed the mesenteric vessels, but with no invasion (fig. 2), being intense vascularised (fig. 3). The haematological investigations revealed minor colestatic syndrome (serum gamma glutamyl transpeptidase = 929 U/L; serum alkaline phosphatase = 1230 U/L) and hyperglycaemia (serum glucose level a jeune = 214 mg/dl). Serum carbohydrate antigen 19-9 was normal.

Indications for surgery in this case where: large tumour, colestatic syndrome (due to the tumour compression), unclear differentiation of benign / malign cystic tumour.
The intraoperative exploration after median laparotomy showed a large multilocular cystic tumour mass in the pancreatic head, with 9.5/9 cm diameters and with compression of the second part of the duodenum and distal part of the common bile duct but with no vascular invasion (fig. 4). A standard Whipple pancreatoduodenectomy (fig. 5) was performed using the posterior approach. Macroscopically the sectioned tumour presented microcystic areas and fibrosis (fig. 6). The standard microscopic examination (Hematoxilin-Eosine) of the operative specimen revealed a serous cysta-denoma of the pancreatic head with no malignancy.
The postoperative course was uneventful excepting a transitory ischemic heart attack remitted after specific medical treatment, the patient being discharged from the hospital on the 13th postoperative day.
Ten months following the surgery, the patient is asymptomatic, with no imagistic signs of recurrence and with no abnormal serum tests (the serum glucose level is maintained within normal ranges under diet and oral antidiabetic therapy).

Discussion
Serous cystadenoma of the pancreas is a benign tumour, usually presenting as a large mass (1, 2). There are still many controversies regarding the differential diagnosis and indications for surgery for cystic tumours of the pancreas (7). Symptomatic cystic tumours should be resected (3). There are authors that reports a certain entity called serous cystadenocarcinoma which is microscopically identical to serous cystadenomas, the only clue to distinguish the malignant variants from benign ones being the tumour behaviour (8, 9).
However, the main differential diagnosis of serous cystadenoma is with mucinous cystic tumours, potentially malignant. Mucinous cystic tumours have some distinctive clinico-pathologic characteristics: they are seen almost exclusively in per menopausal female patients and are located mainly in the tail of the pancreas. On the other side, macroscopically, both tumours are composed of large multilocular cysts ranging in size from one to several centimetres (1).
Despite recent improvements in imaging diagnostic, the preoperative accurate diagnosis of cystic lesions of the pancreas is still difficult. Enhanced abdominal CT is considered the examination of choice for a correct prediction of cystic tumour type (6) establishing the diagnosis in the majority of the cases (10). Serous cystadenomas of the pancreas have a wide range of CT findings, experience of the examinator being the most relevant factor for an accurate diagnosis (11). In 10% of patients with serous cystadenoma are revealed calcification of the tumour (5). Needle biopsy and aspiration with cystic fluid analysis is considered a helpful and safe procedure to aid in the diagnosis of cystic pancreatic neoplasms before surgery (10,12), but is unlikely to provide a high level of diagnostic accuracy necessary to permit a nonoperative approach (13).
Indications for surgery in cystic tumours of the pancreas are considered: symptomatic cysts, cystic tumours that are not clearly defined or suspected cystic tumours, cystic lesions in the body and tail in middle-aged women, serous cystadenoma larger than 4 cm, mucinous cystadenoma (3, 5, 6, 14, 15). The operative procedures should be as limited as possible if no evidence of malignancy is noted preoperatively (7). Surgical centres with large experience in pancreatic surgery claims that surgical resection is recommended in all cystic tumours of the pancreas, even in serous cystic tumours because symptoms may develop and malignant transformation to serous cystadeno carcinoma is possible (16).
For large multilocular cystic tumours located in the head of the pancreas, with uncertain diagnosis, the cephalic pancreatoduodenectomy remains probably the most reasonable type of operation. In case of uncertain involvement of the mesenteric vessels or portal vein, the posterior approach can be a useful and safe method for Whipple/Traverso procedure offering an early selection of patients suitable for resection, avoiding possible intraoperative accidents secondary to anatomical arterial abnormalities (17). When performed in experienced surgical centres this types of operations can be safely done, with low mortality rate and acceptable morbidity rate (18), even in the elderly patients (19).

Conclusions
Preoperative differential diagnosis in large cystic tumours located in the pancreatic head can be very challenging despite modern medical imaging.
Surgical resection is recommended in all cystic tumours of the pancreas, even in serous cystic tumours because symptoms may develop and malignant transformation to serous cystadenocarcinoma is possible.
When performed by experienced surgical teams this kind of operations can be safely done even in aged patients, with reasonable morbidity and mortality rates and good postoperative outcome.

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