Solid-pseudopapillary tumor of the pancreas: clinical features, pathological characteristics, and origin

Objective: [corrected] To study clinically pathological features and origin of solid-pseudopapillary tumor of pancreas (SPT).

Patients and methods: Clinical and pathological data of 82 cases with SPT were retrospectively studied. SAS6.12 statistics package was used for analysis. P < 0.05 was regarded as statistically significant difference.

Results: The SPT patients included 70 females and 12 males, with a median age of 31 years old. The mean tumor size was 6.71 ± 4.42 cm. Vascular or organs was invaded in nine cases. The clinical and pathological characteristics show no significant difference between male and female patients. In the non-encapsulate group (22 cases), the tumor was larger (P = 0.0015), exogenous growth pattern (P = 0.0194), and would probably involve major vascular or organs (P = 1.697E-06). The typical features of SPT include pseudopapillary pattern with fibro vascular stalks by uniform poorly cohesive polygonal cells. The tumor cell expresses a variety of immune markers in heterogeneity. Under electron microscope, there are some electron dense granules, about 8-1.2 µm in diameter, with membrane similar to the zymogen granules in SPT cell cytoplasm.

Conclusions: SPT with incomplete capsule often presents malignant behaviors. SPT shows multi-heterogeneity, which is caused by the disorder in the development of pancreatic stem cell.