Accuracy of diagnosis of solid pseudopapillary tumor of the pancreas on fine needle aspiration: A multi-institution experience of ten cases.

INTRODUCTION

Solid pseudopapillary tumor of the pancreas (SPTP) is a neoplasm of uncertain origin and indolent biologic behavior with distinctive morphological features occurring predominantly in young women. This tumor has an excellent prognosis compared to neuroendocrine and acinar cell carcinoma, which are close differential diagnoses based on morphology, hence making it crucial to diagnose SPTP correctly.

OBJECTIVES

To discuss the cytomorphological features of 10 cases of SPTP reported in two institutions and to evaluate the diagnostic accuracy of endoscopic ultrasound (EUS) guided fine needle aspiration (FNA) cytology in establishing the diagnosis of SPTP.

METHODS

Ten diagnosed cases of SPTP were retrieved from the computerized endoscopy and pathology databases of our two tertiary care institutions. Nine patients had subsequent histological follow-up available. Eight patients underwent EUS-FNA while one patient each had ultrasound and computed tomography-guided FNA. The rapid on-site evaluation was carried out in all 10 cases, and additional material was retained for cell block preparation. Immunohistochemical (IHC) stains ranging from synaptophysin, progesterone receptor, chromogranin, β-catenin, CD10, and NSE were applied on cell blocks. Histological sections of all resected specimens were reviewed, and findings were correlated with those obtained by FNA.

RESULTS

Adequate material was obtained in all ten cases. IHC stains helped to confirm the cytological impression of SPTP. Histological examination of resection specimens, available in 9/10 cases, confirmed the cytological diagnosis.

CONCLUSIONS

FNA particularly that obtained with EUS guidance is an effective tool in the accurate diagnosis of SPTP.