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