A Solid Pseudopapillary Neoplasm in a 10-Year-Old Boy Diagnosed by Endoscopic Ultrasound-Fine-Needle Aspiration (EUS-FNA)

Abstract

The incidences of pancreatic neoplasms are exceedingly rare during childhood and adolescence. Most common among pancreatic neoplasms are solid pseudopapillary neoplasm (SPN) of the pancreas, a rare pancreatic neoplasm with low malignant potential that occurs predominantly in young females. We present a case of SPN with cytomorphological, immunohistochemical, and also histomorphological findings in a 10-year-old boy diagnosed by endoscopic ultrasound-fine-needle aspiration.

INTRODUCTION

Solid pseudopapillary neoplasm (SPN) is a pancreatic tumor with a relatively rare incidence. It constitutes 2%–3% of primary pancreatic tumors in all age groups.[1] Approximately 6%–8% of all SPNs are seen in the pediatric age.[2] It is especially seen more frequently in female (F:M, 8–20:1) and in the adolescent-young adult ages (mean age: 22–25).[3,4] The differential diagnosis of SPN includes pancreatic neuroendocrine tumor (PanNET), pancreatoblastoma, and acinar cell carcinoma due to their similar clinical, radiological, and pathological findings.[2] Due to the rarity of the case and the difficulty of diagnosis with fine-needle aspiration (FNA), we present the case of a10-year-old boy, diagnosed with SPN by endoscopic ultrasound-FNA (EUS-FNA) together with its histopathological correlation.

CASE HISTORY

A previously healthy 10-year-old boy patient presented to the pediatric clinic with pruritic erythematous plaques all over his body. The primary etiology was thought to be allergy. Despite topical and systemic treatment, the patient’s complaints continued to deteriorate, his liver function tests became abnormal, and he lost 10 kilos within 6 months after the first application. The patient was investigated for malignancy, and computed tomography (CT) revealed a 2.2-cm-diameter, well-circumscribed, hypodense mass in the head of the pancreas without contrast enhancement. The SUVmax value of this mass was 6.7 on positron emission tomography/CT imaging. EUS-FNA was performed on the detected mass subsequently. A Papanicolaou staining (PAP) and a May–Grunwald–Giemsa (MGG) staining conventional slide, a PAP-stained liquid-based-cytology slide, and a cell block were prepared. In cytological examination, the smears were cellular and characterized by branching capillaries surrounded by discohesive medium-sized neoplastic cells that have round, oval nuclei with vesicular chromatin, some with prominent nucleoli. There were loosely arranged sheets of tumor cells in some areas [Figure 1a–d]. Tumor cells were strongly positive for β-catenin (nuclear and cytoplasmic), BCL-1, CD10, and vimentin immunohistochemically [Figure 1e–h]. There was no immunoreactivity with synaptophysin [Figure 1i]. The case was diagnosed as SPN with these findings. Whipple surgery was performed after cytological diagnosis. On gross examination of the resection material, a well-circumscribed, soft, cream-colored, well-circumscribed tumor measuring 2.7 × 2.2 × 2 cm was observed at the head of the pancreas. No tumor was seen in the surgical margins. On histopathological examination of the resection material monomorphic, polygonal or oval tumor cells with prominent pink or hyaline cytoplasm were seen. Most tumor cells arranged in sheets with a pseudopapillary architecture [Figure 2a]. The findings of the immunohistochemical study were similar to those obtained from the cytologic samples, and the tumor was positive for β-catenin (nuclear and cytoplasmic), vimentin, CD10, and BCL-1 [Figure 2b–e]. There was also loss of E-cadherin expression [Figure 2f]. There was no immunoreactivity with chromogranin [Figure 2g]. Some eosinophilic globules were detected in or outside the cytoplasm in focal areas which were positive with periodic acid–Schiff and diastase-resistant periodic acid-Schiff (DPAS) on histochemical staining [Figure 2h–i]. The general clinical condition of the patient improved after Whipple surgery. The patient has been continuing his clinical follow-up regularly for approximately 1 year. No pathological findings were detected in the control imaging performed after the Whipple operation.

Figure 1.

(a) Cellular aspirate with branching pseudopapillary fragments, central delicate capillaries, and discohesive cercariform cells around (PAP ×100). (b) Highly cellular smear (May Grunwald Giemsa × 100). (c) Central pseudopapillary fragment and discohesive cercariform cells around (PAP liquid-based-cytology ×400). (d) Uniform, round-nucleated, medium-sized tumor cells with eosinophilic cytoplasm (H&E ×200). (e) Tumor cells positive for β-catenin (β-catenin ×200). (f) Tumor cells positive for BCL-1 (BCL-1 ×200). (g) Tumor cells positive for CD10 (CD10 ×200). (h) Tumor cells positive for vimentin (vimentin ×200). (i) Tumor cells negative for synaptophysin (synaptophysin ×200)

Figure 2.

(a) Monomorphic tumor cells arranged in sheets with pseudopapillary configuration in between normal pancreatic tissue (H&E ×200). (b) Tumor cells positive for β-catenin (nuclear and cytoplasmic) (β-catenin ×200). (c) Tumor cells positive for vimentin (vimentin ×200). (d) Tumor cells positive for CD10 (CD10 ×200). (e) Tumor cells positive for BCL-1 (BCL-1 ×200). (f) Loss of E-cadherin expression in tumor cells (E-cadherin ×200). (g) Tumor cells negative for chromogranin (chromogranin ×200). (h) Hyalin globules positive with periodic acid–Schiff (PAS) (PAS ×200). (i) Hyalin globules positive with diastase-resistant periodic acid-Schiff (DPAS) (DPAS ×200)

DISCUSSION

Although the age of patients ranged widely, the SPN of pancreas are neoplasms of low malignant potential found predominantly in young females, and it accounts for 2%–3% of all pancreatic tumors.[1] SPN is classified in the Neoplastic: Other category according to the Papanicolaou Society of Cytopathology reporting system and in the malignant category according to the World Health Organization International Pancreaticobiliary Cytopathology Reporting System. The differentiation of SPN from other pancreatic neoplasms can be difficult with atypical findings. PanNET, acinar cell carcinoma, and pancreatoblastoma are included in the differential diagnosis because of their morphological overlapping features.[2] SPN and PanNET can have similar cytomorphological and histomorphological features. Solid tumor areas with small-to-medium-sized uniform oval–round nuclei and eosinophilic cytoplasm can be seen in both neoplasms.[3] Finely granular chromatin (salt-and-pepper appearance) seen on PanNET is helpful in the differential diagnosis. In addition, nuclear expression of β-catenin and loss of E-cadherin expression are seen in almost all SPN, while the cytoplasmic and membranous expressions of β-catenin and strong immunoreactivity with E-cadherin are mostly seen in PanNET.[3] Although synaptophysin may be positive in some SPNs (55%), chromogranin expression is very rare (9%). However, diffuse synaptophysin positivity and variable chromogranin expression are seen in PanNETs.[4] In our case, we excluded the diagnosis of PanNET due to the presence of β-catenin nuclear expression, absence of salt-and-pepper chromatin, and negative neuroendocrine immunohistochemical markers.[5] Acinar cell carcinoma is another malignant neoplasm of pancreas that is highly cellular and characterized by prominent acinar formation without squamoid nests and pseudopapillary architecture.[5] Tumor cells have a single, prominent nucleolus and moderate amounts of granular eosinophilic cytoplasm.[6] It is positive for trypsin, chymotrypsin, lipase, and BCL10 and negative for β-catenin, CD56, and CD10 generally.[5] Pancreatoblastoma is a malignant epithelial tumor composed of primitive polygonal cells with hypercellular stroma and the defining characteristic squamoid nests with predominantly acinar differentiation.[2,5] Neoplastic cells have prominent central nucleoli and granular eosinophilic cytoplasm containing DPAS-positive zymogen granules.[5] Tumor cells were positive for trypsin, chymotrypsin, BCL10, and lipase.[2,5]

In conclusion, although it has been reported that SPN cases are more common in females and adolescent–young adult ages, this study reports the case of a 10-year-old boy. In addition, our patient was diagnosed with SPN by EUS-FNA. These are important features that distinguish our study from many others in the literature and make it rare. Since SPN constitutes for more than half of pediatric pancreatic neoplasms (70%), SPN should be considered in the differential diagnosis of pediatric FNAs. PanNET, acinar cell carcinoma, and pancreatoblastoma are included in the differential diagnosis because of their overlapping morphological features. Immunohistochemical study can be helpful in the differential diagnosis.

Author contributions

The division of work among the contributors as follows; BA (Guarantor): concepts, design, definition of intellectual content, literature search, clinical studies, experimental studies, data acquisition, data analysis, manuscript preparation, manuscript preparation, manuscript editing, and manuscript review. SE-D: manuscript preparation, manuscript editing, and manuscript review, definition of intellectual content, literature search, and clinical studies. OY: literature search, clinical studies, experimental studies, data acquisition, data analysis, and manuscript review. RSA: literature search, clinical studies, experimental studies, data acquisition, data analysis, and manuscript review.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.