Primitive neuroectodermal tumors (PNETs) are presented as rare malignant neoplasms. In unusual cases, those neoplasms may arise in solid organs containing neuroendocrine cells, such as the pancreas. Herein the case of a 28-year-old patient that underwent gastroduodenopancreatectomy after the diagnosis of a huge mass (PNET) located in both head and body of the pancreas is reported. This is the 19th case of pancreatic PNET reported in literature.
Primitive neuroectodermal tumors (PNETs) are presented as rare malignant neoplasms, showing different degrees of differentiation. They are often classified as small round cell tumors arising from soft tissues. PNETs also integrate Ewing’s sarcoma family of tumors (ES), which represents 1% of all sarcomas [
In rare cases, PNETs may arise in solid organs containing neuroendocrine cells, with previous reports on kidneys, urinary bladder, ovaries, uterus, parotid glands, heart, and lungs [
These neoplasms occur predominantly in pediatric and teenaged populations [
A proper integration of the pathological, clinical, immunohistochemical, and cytogenetic findings is necessary for a successful diagnosis of pancreatic PNETs and also for distinguishing this group from other neoplasms with similar presentations [
In spite of the poor prognosis, surgical treatment followed by chemotherapy or radiotherapy or both is the most widely accepted option, given the aggressiveness of such neoplasms [
A 28-year-old female patient was admitted to the Emergency Department of Santa Casa Hospital in Porto Alegre, Brazil. She was referring epigastric pain for 14 days, with partial relief due to the use of weak analgesics. The pain was associated with diffuse cutaneous pruritus, jaundice, choluria, and acholia.
On physical examination, the patient was in a good general condition, jaundiced, with a hardened palpable mass in the epigastric and right hypochondrium regions. Laboratory tests showed a cholestatic pattern (Table
Laboratorial findings.
Total bilirubin | 4 mg/dL |
Direct bilirubin | 3,1 mg/dL |
Alkaline phosphatase | 319 U/L |
Gamma-glutamyl transpeptidase | 136 U/L |
Glutamic-oxaloacetic transaminase | 371 U/L |
Glutamic-pyruvic transaminase | 759 U/L |
CA19-9 | 2,9 U/mL |
CEA | 3,0 ng/mL |
Initially, an abdominal ultrasonography was performed, revealing a voluminous heterogeneous hypoechoic mass measuring about 13 cm width, 9 cm length, and 13 cm height. It presented cystic areas inside, between left hepatic lobe and pancreas. It was not possible to determine the origin of the mass. Dilatation of intrahepatic bile ducts and proximal common bile duct was also referred to (Figure
Abdominal ultrasonography showing a huge heterogeneous mass.
Computerized tomography with intravenous contrast unfolds a voluminous expansive lesion in pancreatic head and body, with well delimited borders, measuring about 12.8 × 12.1 × 10.9 cm. A heterogeneous density due to the presence of both liquid and solid areas is also shown in the CT. The image showed intense enhancement of an intravenous contrast agent. The lesion displaced adjacent structures, although no infiltration was detected. A significant ectasia of the intrahepatic and extrahepatic bile ducts could also be seen (Figure
Abdominal CT reveals a voluminous lesion in pancreatic head and body (arrow).
The patient was evaluated by the hepatopancreatobiliary team and underwent a gastroduodenopancreatectomy, performed uneventfully. The gross appearance of the lesion was a solid cystic mass, was encapsulated and multiloculated, and was with necrotic aspect areas, measuring a total of 11.5 cm along its longest axis (Figure
Surgical specimen.
The pathological study revealed a neoplasm of small round blue cells with scant cytoplasm arranged in nests with fibrovascular stroma. Few mitosis pictures and several areas of necrosis were also found. Immunohistochemistry was strongly positive for CD99 (Figure
Small round cells with scant cytoplasm; immunohistochemistry was positive for CD99.
The patient recovered well postoperatively, presenting normalized levels of bilirubin, alkaline phosphatase,
Primitive neuroectodermal tumors (PNETs) represent about 1% of all sarcomas and have a five-year survival rate of approximately 50% [
Histologically, the ES family of tumors is made of small monomorphic round cells with small nuclei and scant cytoplasm; nonetheless, there is a large group of tumors with the same pattern [
An association of pathological, immunohistochemical, clinical, and cytogenetic features is, therefore, required for diagnosing pancreatic PNETs [
Immunohistochemistry is extremely useful in diagnosing this neoplasm, as peripheral primitive neuroectodermal tumors substantially express a cell surface glycoprotein. This glycoprotein is product of the MIC2 gene (a pseudoautosomal gene located on the short arm of the X and Y chromosomes of PNETs and ESs cells), also called CD99 or p30/3
Regarding the clinical presentation, it can be said that there is no specific set of symptoms for pancreatic PNETs. The onset of the disease seems to be insidious and producing few symptoms, with abdominal pain during palpation of the mass being the most referred to symptom. Mao et al. [
Bose et al. [
Among imaging tests, abdominal CT and MRI are the most used in the detection of these tumors. The diagnosis is not easy, as there is no pattern of radiological findings. The commonly found one, however, consists of masses with clear margins in the head of the pancreas [
Discussing again the compilation of 16 patients of Bose and colleagues [
The PNETs are characteristic aggressive tumors. Studies have shown that 25–30% of patients presented metastasis at diagnosis of PNET and it is believed to be an even larger number of patients with micrometastasis [
Moschovi et al. [
Movahedi-Lankarani et al. [
In spite of being an extremely rare disease, pancreatic PNETs should be considered in the differential diagnosis of pancreatic mass research, especially in patients younger than 35 years. Cases with undifferentiated small cell carcinoma, pancreatoblastoma, neuroendocrine carcinomas, and pancreatic endocrine tumors should also be investigated for PNETs. The clinical presentation of the tumor is diffuse and its histological findings are not exclusive. Most patients have a rapid growth mass, with nonspecific clinical symptoms and, often, abdominal pain.
These tumors present themselves as highly aggressive tumors with almost inevitable recurrence and metastasis, which makes the overall five-year survival rate reach almost 50%. Despite significant advances in treatment, there is still no definitive conclusion on which is the best therapeutic strategy at the moment.
The authors declare that there is no conflict of interests regarding the publication of this paper.