[Difficulties of differential diagnosis of pancreatic pseudocysts and cystic neoplasms]

Abstract

Objective: Surgical resection is indicated in potentially malignant pancreatic cystic neoplasms. Drainage operations are performed in large (5-6 cm) and/or symptomatic pseudocysts. Misdiagnosis results in a considerable delay in an appropriate treatment. Our aims were to compare clinical, morphological, biochemical features of cystic neoplasms and pseudocysts, in which diagnosis of cystic neoplasm was suspected preoperatively, and to determine characteristics, which could predict the misdiagnosis of cystic neoplasms as "pseudocysts".

Material and methods: One hundred and thirty four patients were operated because of pancreatis cystic lesions (22 cystic neoplasms and 112 pseudocysts) between January 1999 and May 2004. Two groups of patients were evaluated retrospectively. Group I included 22 (10 serous and 8 mucinous cystoadenomas, 3 mucinous cystadenocarcinomas, 1 solid papillary tumor) resected neoplasms. Group II included 11 patients in whom neoplasm was suspected during investigation, but definitive diagnosis of pseudocyst was established. Clinical manifestation, morphologic characteristics and data of instrumental investigations were also compared. Preoperative and postoperative diagnoses were compared with histopathological findings.

Results: Women predominated in group I (67.2%) and men in group II (81.2%). Group I patients were older (mean age 57.9+/-14.55 versus 49.27+/-10.07 years). All pseudocysts were symptomatic. Two (9.1%) incidental cystic neoplasms and 2 drainage operations were performed previously because of misdiagnosed "pseudocysts" in other hospitals. Abdominal pain, 81.8% and 100%, and abdominal mass, 31.8% and 54.4%, were recorded most frequently, group I and group II respectively. Neoplasms (median diameter 59.6 mm) were mainly located in pancreatic head (31.8%) and body (36.4%). Most of pseudocysts (median diameter 71.1 mm) were located in pancreatic head (45.5%). Diagnostic sensitivity of ultrasonography (86.4%) and computed tomography scan (84.2%) was higher in group I than in group II (63.6% and 77.8%). Two serous oligocystic and 1 mucinous cystoadenomas were misdiagnosed as "pseudocyst" preoperatively. In one case malignancy of mucinous tumor diagnosed only postoperatively.

Conclusions: Differentiating serous and mucinous cystoadenomas from pseudocysts may be difficult. Malignant neoplasms may be undetermined preoperatively. Resection should always be performed in instances where findings cannot be clearly identified.