Discussion
A pancreatic solid pseudopapillary neoplasm (SPN) is a rare exocrine pancreatic tumor and accounts for 1-3% of all pancreatic tumors.1 It was first described by Frantz in 1959.2 SPN has a female predominance with a female to male ratio of 10:1. Additionally, it predominantly occurs in Asian and African American women. Women usually present at a younger age compared to men with the mean ages for females and males at the time of presentation being 25 and 35, respectively.3,4 Typical clinical manifestations include vague abdominal pain (40%) and palpable abdominal mass (33%). Some patients may have poor appetite and nausea which may be secondary to compressive effects of the tumor on the stomach and adjacent organs.5,6 However, 20% of females and up to 40% of males are asymptomatic6. SPN is a rare occurrence in men. The common location of the mass in male patients is body-tail region which account up to 65% of the total cases; the location in females usually involves the pancreatic head.5
Solid pseudopapillary neoplasms is detected by imaging incidentally in asymptomatic patients. Multiple imaging modalities for SPN can be utilized. Abdominal ultrasound shows a hypoechoic, clear-bordered cystic or cystic-solid mass. Computed tomography and magnetic resonance imaging of abdomen describe a large well-circumscribed lesion with heterogenous density and solid and cystic components.6,7 Endoscopic ultrasound (EUS)-guided fine needle aspiration and biopsy (FNA/B) is diagnostic.8
The tumor markers for pancreatic cancer are usually negative in patients with pancreatic SPN. These markers include the carcinoembryonic antigen (CEA), serum cancer antigen (CA) 19-9, and serum CA 72. Tumor markers are elevated in less than 10% of patients with SPN. Therefore, no tumor markers or specific laboratory test have been established for diagnosing pancreatic SPN to date. The definite diagnosis is mainly based on imaging studies and pathological tissue analysis from FNA/FNB specimens.
The risk of malignant potential is estimated to be around 15%. The tumor can be locally aggressive and extend into adjacent blood vessels and organs. There is potential for local recurrence and distance metastasis.8 Distant metastases were reported in about 4% cases at the time of diagnosis. According to a multicenter study by Matos, surgical resection is the treatment of choice for SPN.9 Patients have an excellent prognosis with 5-year survival rate as high as 97% in patients undergoing surgical resection and 10-year survival rate at 96%.5,10,11