Institutional experience with solid pseudopapillary neoplasms: focus on computed tomography, magnetic resonance imaging, conventional ultrasound, endoscopic ultrasound, and predictors of aggressive histology.

OBJECTIVE: Solid pseudopapillary neoplasms (SPNs) are low-grade malignancies with an excellent prognosis, albeit with the potential for metastatic disease. This study details our institution's experience with the diagnosis and treatment of SPN, including clinical presentation, multimodality imaging findings, and potential predictors of aggressive tumor behavior.
MATERIALS AND METHODS: The institutional pathology database was searched through for all cases of SPN since 1988, yielding 51 patients. The electronic medical record was searched for clinical and demographic information regarding these patients, including age, sex, presenting symptoms, type of surgery, postoperative length of stay, tumor markers, and postsurgical follow-up. All available imaging data were reviewed, including those of 30 patients who underwent multidetector computed tomography, those of 9 patients who underwent magnetic resonance imaging (MRI), those of 3 patients who underwent conventional ultrasound, and those of 11 patients who underwent endoscopic ultrasound.
RESULTS: A total of 84% of patients were females, with a mean age of only 33 years. Prognosis was excellent, with a mean follow-up of 3 years without recurrence. Only 1 of the 51 patients developed metastatic disease to the liver 8 years after the surgery. On computed tomography, lesions tended to be large (5.3 cm), well circumscribed (29/30), round/oval (20/30), and encapsulated (23/30). The lesions often demonstrated calcification (14/30) and typically resulted in no biliary or pancreatic ductal dilatation. The lesions ranged from completely cystic to completely solid. On MRI, the lesions often demonstrated a T2 hypointense or enhancing capsule (6/9) and demonstrated internal blood products (5/9). The lesions tended to be devoid of vascularity on conventional ultrasound. Ten patients were found to have "aggressive" histology at presentation (T3 tumor, nodal involvement, perineural invasion, or vascular invasion). No demographic, clinical, or multidetector computed tomographic imaging features were found to correlate with aggressive histology.
CONCLUSIONS: Certain imaging features (eg, well-circumscribed mass with calcification, peripheral capsule, internal blood products, and lack of biliary/pancreatic ductal obstruction) on computed tomography and MRI are highly suggestive of the diagnosis of SPN, particularly when visualized in young female patients. However, it is not possible to predict aggressive histology on the basis of imaging findings, clinical presentation, or patient demographic features.