Imaging features of primary malignant pancreatic tumors in children

Comparison between pancreatoblastoma (PB) and solid pseudopapillary neoplasm (SPN) in pediatric patients with enhanced CT

RATIONALE AND OBJECTIVES

To investigate whether computed tomography features can differentiate pancreatoblastoma (PB) from solid pseudopapillary tumor (SPN) in children.

MATERIALS AND METHODS

Clinical and imaging data of 18 cases of PB and 61 cases of SPN confirmed by surgery or biopsy were retrospectively analyzed. All enrolled patients underwent 3 phases (non-contrast, arterial, and portal venous phases) of CT scanning. Qualitative CT analysis (location, margin, solid/cystic component proportion, calcification, hemorrhage, peritumoral vascularity, bile duct dilatation, pancreatic duct dilatation, pancreatic atrophy, vascular invasion, peripancreatic invasion, and distant metastases) and quantitative analysis (maximum tumor diameter, interface between tumor and parenchyma [delta], arterial enhancement ratio [AER], and portal enhancement ratio [PER]) were performed. The general CT morphologic features, age and tumor markers were compared also compared between the groups. Univariate analysis and the F test were conducted to identify features of PB. Then logistic Regression classifier was trained using the top five features with the highest F-value. Moreover, we used 5-fold cross-validation techniques for the validation of our model.

RESULTS

PB exhibited a significantly higher frequency of location in the body/tail, larger tumor size, poorly defined margins, calcification, peritumoral vascularity, pancreatic atrophy, and less hemorrhage. In addition, PB had higher AER, PER and lower delta relative to SPN (p < 0.05). PB presented a younger age and higher levels of AFP. Results of the F test indicated that AFP, AER, Age, calcification and pancreatic atrophy were the top five features included in the model that could differentiate pediatric PB from SPN. The combined model of CT and clinical features performed well in differentiating PB from SPN, with an AUC of 0.981 in the training cohort and 0.953 in the validation cohort.

CONCLUSIONS

AFP, AER, age, calcification and pancreatic atrophy are robust CT and clinical features for differentiating pediatric PB from SPN. A combination of qualitative and quantitative CT features may provide good diagnostic accuracy in differentiating PB from SPN in children.

Solid pseudopapillary neoplasms of the pancreas in childhood and adolescence-an analysis of the German Registry for Rare Pediatric Tumors (STEP)

Solid pseudopapillary neoplasms (SPNs) are the most common entity among pediatric pancreatic tumors. Still, these are rare tumors with an annual incidence of 0.1-0.2/1,000,000, and little is known about their optimal treatment. This analysis aimed to increase knowledge about the occurrence and treatment strategies of SPN in childhood. Data regarding diagnostics, treatment, and outcome of children aged 0-18 years with SPN recorded in the German Registry for Rare Pediatric Tumors (STEP) were analyzed. Thirty-eight patients were identified with a median age of 14.5 years at diagnosis (range: 8-18) and a female preponderance (81.6%). The most frequent location of the tumor was the pancreatic tail. In histopathological and immunohistochemical examination, pseudopapillary, solid, and cystic lesions as well as expression of beta-catenin, progesterone receptors, and cyclin D1 were the most common findings. All patients underwent surgical resection. Most patients underwent open resection, predominantly tail resection for tumors in the tail region and pylorus-preserving pancreaticoduodenectomy for tumors in the head region. The main postoperative sequela was exogenous pancreatic insufficiency (23.7%), especially with SPN in the pancreatic head. No recurrence occurred during follow-up, although two patients underwent resection with microscopic residue.

CONCLUSION

SPN of the pancreas in childhood are low-grade malignancies with usually favorable treatment outcomes. However, therapy can lead to relevant long-term sequelae. To prevent recurrence, complete surgical resection is recommended, sparing as much healthy pancreatic tissue as possible. Interdisciplinary collaboration between specialists is essential to optimize treatment. Molecular genetic analysis of these tumors could improve understanding of their genesis.

WHAT IS KNOWN

• Solid pseudopapillary neoplasms (SPNs) of the pancreas are very rare tumors in childhood. • Little is known about tumorigenesis, and there are no specific guidelines for treatment and follow-up in pediatric patients.

WHAT IS NEW

• Characteristics, treatment, and outcome were comprehensively assessed in a large cohort of pediatric patients with SPN. • We propose recommendations for diagnosis, treatment, and follow-up of children with SPN, based on our analysis and considering published experience.

Differential diagnosis of pancreatoblastoma (PB) and solid pseudopapillary neoplasms (SPNs) in children by CT and MR imaging

OBJECTIVES

To determine whether features on computed tomographic and/or magnetic resonance imaging can differentiate pancreatoblastoma (PB) from solid pseudopapillary neoplasms (SPNs) of the pancreas in children.

METHODS

Clinical and imaging data for 20 cases of SPNs and 14 cases of PB confirmed by surgery or biopsy were retrospectively analysed. The size, border, calcification, haemorrhage, solid/cystic component proportion, intratumoural vessels, tumour capsulation, pancreatic duct dilatation, peripancreatic vessel invasion, distant metastasis status and apparent diffusion coefficient (ADC) values of the two groups were examined, and key diagnostic features were identified. Statistical analysis was performed using the chi-square test and Student's t test. Sensitivity and specificity values were calculated when a single criterion was used.

RESULTS

Age ≤ 5 years, elevated serum α-fetoprotein (AFP), larger size, ill-defined border, calcification, absence of haemorrhage, intratumoural vessel, peripancreatic vessel invasion and distant metastasis differentiated PB from SPN (p < 0.05). ADC values of SPN were higher than those of PB (p = 0.001). There were no significant differences regarding tumour capsule (p = 0.435), pancreatic duct dilatation (p = 1.000) or cystic degeneration area over 50% of the tumour volume (p = 1.000) between the two groups.

CONCLUSIONS

The following features are helpful for differentiating PB from SPN: age ≤ 5 years, elevated serum AFP, larger size, ill-defined border, calcification, haemorrhage absence, intratumoural vessel, peripancreatic vessel invasion, distant metastasis and lower ADC value.

KEY POINTS

• CT and MRI are helpful to differentiate pancreatoblastoma (PB) from solid pseudopapillary neoplasms (SPNs) of the pancreas in children. • The following features are helpful to differentiate PB from SPN: age ≤ 5 years, elevated serum AFP, larger size, ill-defined border, calcification, absence of haemorrhage, intratumoural vessel, peripancreatic vessel invasion, distant metastasis and lower ADC value.

Adult pancreatoblastoma - Case report and review of literature

Most cases of pancreatoblastoma, a rare malignant epithelial tumor of the pancreas, are seen in the pediatric population. The rarity of pancreatoblastoma, the similar radiologic findings to those seen in other pancreatic lesions, and its histopathologic heterogeneity, make its preoperative diagnosis in adults a real challenge. We report ultrasound, computed tomography and magnetic resonance imaging correlative findings of a histologically proven pancreatoblastoma in a 37-year-old woman. Pancreatoblastoma should be considered in the differential diagnosis of a pancreatic mass presenting uncommon imaging features.