[Study on clinicopathologic features and metastasizing potential of solid pseudopapillary tumor of pancreas]

To study the clinicopathologic features and metastasizing potential of solid pseudopapillary tumor of the pancreas (SPT).

Forty-five cases of SPT were retrieved from the archival file and subdivided into metastasizing group (MG, n = 4), and non-metastasizing group (NMG, n = 41), according to the follow-up clinical information. The histological features were reviewed and immunohistochemical study for vimentin, alpha 1-antitrypsin, alpha 1-antichymotrypsin, CD10, neuron-specific enolase, progesterone receptor, chromogranin A, synaptophysin, AE1/AE3, beta-catenin, p53, cyclin D1, CD34 and Ki-67 was carried out. The results were correlated with follow-up data.

There was no statistically significant difference between MG and NMG, in terms of age and gender of the patients, site, size and capsular status of the tumor. No single morphologic parameter could distinguish MG from NMG. In general, increased mitotic activity, tumor emboli in vessels and necrotic foci were more conspicuous in MG than in NMG. According to a morphologic scoring system, all cases of MG had score ≥ 5, in contrast to < 5 in 95.1% (39 cases) of NMG. Immunohistochemically, there was no statistically significant difference between MG and NMG for beta-catenin, p53, cyclin D1 and CD34 staining. Ki-67 positivity however was significantly higher in MG. Amongst the 37 cases with follow-up information available, the average duration of follow up was 37.4 months. Thirty-three patients were alive and disease-free.Four suffered from liver metastases; and none of them died of the tumor.

Mitotic activity, presence of tumor emboli and necrotic foci represent as the useful parameters in predicting metastasizing potential of SPT, especially with application of morphologic scoring system. Immunostaining for Ki-67 can also serve as an additional prognostic indicator.