The morphological classification of a serous cystic tumor (SCT) of the pancreas and evaluation of the preoperative diagnostic accuracy of computed tomography.

BACKGROUND: Although the honeycomb microcystic type is common and typical for a serous cystic tumor (SCT), clinical and radiological features are diverse. Systematic classification of SCT subtypes is not well established. The purpose of this study was to classify the subtypes of SCT and to clarify its clinical and pathological characteristics.

METHODS: Clinical data from 52 patients with a pathologically confirmed SCT were prospectively collected using a standard data form. According to cyst size and multiplicity, on gross and radiological evaluation, the cysts were classified as microcystic when they were smaller than 2 cm, and macrocystic when larger than 2 cm. The microcystic tumors were subdivided into honeycomb and solid types, while the macrocystic tumors into unilocular and multilocular types based on the number of cysts.

RESULTS: There were 22 cases with microcystic SCTs that were subclassified into the honeycomb (n = 21) and solid types (n = 1), while 30 cases were macrocystic type and were subclassified into multilocular (n = 16) and unilocular types (n = 14). There were no differences between four subtypes with regard to gender, tumor location, and size. The preoperative diagnostic accuracy of the unilocular macrocystic SCT was only 35.7%, while that of honeycomb microcystic SCT and multilocular macrocystic SCT were 81% and 87.5%, respectively (P = 0.005).

CONCLUSION: Microcystic SCTs and multilocular macrocystic SCTs can be accurately diagnosed preoperatively; therefore conservative treatment and observation are possible in some cases. However, the unilocular macrocystic SCT is difficult to differentiate from the other pancreatic cystic tumors with malignant potential, therefore resection must be considered.