Neuro-endocrine tumors are uncommon neoplasms which often present diagnostic challenges to both the radiologist and pathologist.

The clinical evaluation of these pancreatic rare tumors is still suffering from same limitations despite the improvement in the diagnostic tools. Subsequently, the aim of this article is to highlight diagnostic pitfalls and differential diagnosis of these tumors particularly in their cystic form.

A 14-year-old girl was referred by her pediatrician for possible management of a pancreatic cyst discovered on an abdominal ultrasonography. Our patient suffered from abdominal paroxystic pain accompanied by vomiting.

The child was in good general condition. Clinical examination reveals a firm, painless, epigastric mass. The rest of the exam was strictly normal. Ultrasound and abdominal magnetic resonance imaging performed (Figure 1A and Figure 1B) specified a cystic avascular encapsulated lesion of head of pancreas, measuring 48 mm from the long axis oblique out, 45 mm high, 47 mm thick (Figure 2). The pancreatic head was distorted by the cyst pushing the mesenteric vessels toward the periphery, without peritoneal fluid reaction, no perilesional lymph nodes and no communication with the visualized biliary duct.

She underwent exploration laparotomy, which revealed a large cystic swelling with a thick wall. The cyst was dissected and completely removed. Postoperatively, she did well and was discharged home on the eighth postoperative day (Figure 3).

The excised tumor was round, cystic, and well-demarcated with no parietal calcifications.

Histologically, the tumor was composed of sheets of monomorphic medium-sized cells arranged in acinar or glandular pattern, surrounding a lumen, with no visible mitoses or amyloid depositions.

The neuroendocrine differentiation of the tumor is confirmed by the expression of chromogranin and synaptophysin.

Pancreatic cysts are extremely rare in the pediatric age population. Pancreatic pseudocysts following acute pancreatitis, whether post-traumatic or post-inflammatory, are the most frequent. True cysts are extremely rare and classified into six types: congenital, retention, duplication, pseudocysts, neoplastic, and parasitic cysts.

Differentiating clinically and radiologically between these types is very difficult. Pathologically, the first three types, called true cyst are true developmental cysts and are circumscribed by true epithelium unlike the pseudo-pancreatic cysts [1],[2],[3],[4].

Gastro-enteropancreatic neuroendocrine tumors (GEP-NETs) are neural crest tumors whose clinical and imaging features are not well described in children population. These tumors arise from neuro-endocrine cells issued from pancreas, gut, and bronchial tree. The term “neuroendocrine tumors” regroup carcinoid tumors, islet cell tumors, and amine precursor uptake and decarboxylation (APUD) tumors [5].

Neuro-endocrine tumors can be subdivided into malignant and benign entities. They represent 20% of malignant pancreatic tumors in children. They may be associated to multiple endocrine neoplasia type 1, most of which are nonfunctioning. They also may be associated to von Hippel–Lindau syndrome though cystic neoplasms are the most commonly seen pancreatic manifestation of this syndrome [5].

Neuro-endocrine tumors account for only 1–2% of all pancreatic neoplasms and less than 10% of all neuroendocrine tumors are cystic, which makes cystic neuro-endocrine lesions very rare.

The clinical presentation of islet cell neoplasms differs between functional and nonfunctional tumors. Nonfunctional tumors present with nonspecific symptoms related to mass effect. Functional tumors, by contrast, often present earlier with symptoms related to the hyper-secreting hormone [5].

Identification of cystic neuro-endocrine tumors in the pancreas with computed tomography (CT) scan or magnetic resonance imaging (MRI) is extremely difficult [6].

These tumors appear as nonspecific circumscribed hypo-echoic pancreatic masses at ultrasound.

The most frequent imaging feature of neuro-endocrine tumors at contrast-enhanced CT and at MRI is hyper-vascularity. They have a greater degree of enhancement than normal pancreas in both the arterial and venous phases of imaging. Some of neuro-endocrine tumors may be cystic; not communicating with bile ducts, the presence of a hypervascular rim suggests this tumor over cystic pancreatic lesions. General MRI signal-intensity characteristics include T1 hypo-intensity and T2 hyper-intensity relative to the normal pancreatic parenchyma.

Modern imaging techniques usually show a well-defined unilocular cyst; however, even with the combined use of laboratory data, clinical features, and diagnostic imaging, it may be difficult to accurately differentiate congenital pancreatic cyst from other nearby cystic lesions of the abdomen. This is especially true if they are large [6].

Endoscopic ultrasound coupled with fine-needle aspiration has enabled not only the detailed examination of pancreatic cystic lesions but also cytological, biochemical, and immune-cytological analysis [7],[8].

The treatment of neuroendocrine cyst is surgical. The type of surgical treatment depends on the site and size of the cyst. Total excision is the treatment of choice [9],[10].

Although rare, neuro-endocrine tumor should be mentioned among the diagnoses of cystic mass of the pancreas in children.