Solid-pseudopapillary neoplasm (SPN) of the pancreas: case series and literature review on an enigmatic entity.

Solid pseudopapillary neoplasm (SPN) of the pancreas is a rare tumor which typically affects young women without significant clinical symptoms. SPN usually shows an indolent behavior and only rare cases recur and/or metastasize after complete resection. We report our experience with four cases of SPN of the pancreas. All four patients were female with an age range of 15-42 years (mean age: 24.5 years). Two patients presented with abdominal pain, one with abdominal mass and one with acute abdominal signs following blunt trauma. Tumor's size ranged from 1 to 16 cm (mean size: 5.5 cm). Two tumors were diagnosed preoperatively through percutaneous core needle biopsy and two underwent surgery without preoperative diagnosis because of high suspicion of SPN based on clinical and radiological findings. By immunohistochemistry, all cases stained strongly for vimentin, progesterone-receptor and beta-catenin (nuclear) and variably with pankeratin and neuroendocrine markers. The proliferation index (Ki-67) was <2% in all cases. After a median follow-up of 40 months (range: 24-57 months), all patients were alive with no evidence of recurrence or metastatic disease. In conclusion, SPN of the pancreas should be considered in the differential diagnosis of any solid and partly cystic pancreatic or upper abdominal mass, particularly in young females. SPN possesses a low malignant potential and complete surgical resection with clear margins is the treatment of choice. Following R0 resection, SPN has an excellent prognosis.