Endoscopic ultrasound-guided fine needle aspiration cytology diagnosis of solid pseudopapillary neoplasm: three case reports with review of literature

Abstract

Solid pseudopapillary neoplasm of the pancreas (SPN) is relatively rare and it occurs almost exclusively in women. We recently experienced three cases of SPN diagnosed by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA). These three cases were two male and one female patient whose age was 29, 37, and 44 years old. Radiological diagnosis was pancreatic endocrine tumor (PEN) showing solid with a heterogenous echogenicity. EUS-FNA cytology specimens consisted of single cells and aggregates of uniform cells, forming microadenoid structures, branching, papillary clusters with delicate fibrovascular cores. In conclusion, a single diagnosis of SPN based on clinical and radiological findings would be risky because there is a possibility of it being misdiagnosed as PEN or other malignancies. An EUS-FNA is therefore essential for establishing the diagnosis. In addition, the pathologists should recognize the characteristic cytologic findings with immunoprofiles of SPN to prevent misdiagnosis of SPN.

Keywords: Cytology; Endoscopic ultrasound-guided fine needle aspiration; Solid pseudopapillary neoplasm.

Fig. 1

(A) A well-defined, partly enhancing 4.0 cm-sized mass is present in the pancreatic head of case 1 (arrows). (B) An endoscopic ultrasound image shows a 4.0 cm-sized, round, well-defined and heterogeneously hypoechoic solid mass in the pancreatic head. (C) A whitish-tan, solid mass with hemorrhage is noted in the pancreatic head on the resected specimen (arrows).

Fig. 2

(A) In case 1, there are inconspicuous nucleoli (arrowhead) and nuclear grooves (arrow). (B) In case 2, the tumor cells show a rosette formation with a myxoid globule in the background of hemorrhage. (C) Case 3 is characterized by the papillary arrangement composed of delicate fibrovascular core with attached multilayer monotonous cuboidal cells. (D) In case 3, both a cluster of tumor cells and scattered ones are identically showing relatively uniform, monotonous features.

Fig. 3

(A) Some areas of tumor show a solid sheet with thin fibrovascular cores and clear or eosinophilic granular cytoplasm. Intraluminal myxoid globules (B) and eosinophilic hyalinized stroma (C) are frequently observed.

Fig. 4

In case 3, the tumor cells show an immunopositivity for vimentin (A), progesterone receptor (B), and β-catenin (C) and an immunoreactivity for a loss of E-cadherin (D).