Does Computed Tomography Have the Ability to Differentiate Aggressive From Nonaggressive Solid Pseudopapillary Neoplasm?

Preoperative prediction of invasive behavior of pancreatic solid pseudopapillary neoplasm by MRI-based multiparametric radiomics models

OBJECTIVE

A log-combined model was developed to predict the invasive behavior of pancreatic solid pseudopapillary neoplasm (pSPN) based on clinical and radiomic features extracted from multiparametric magnetic resonance imaging (MRI).

MATERIALS AND METHODS

A total of 111 patients with pathologically confirmed pSPN who underwent preoperative plain and contrast-enhanced MRI were included, and divided into an invasive group (n = 34) and non-invasive group (n = 77). Clinical features and laboratory data related to pSPN invasive behavior were analyzed. Regions of interest were delineated based on T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and contrast-enhanced T1WI (CE-T1WI) to extract radiomic features. Correlation analysis was performed for these features, followed by L1_based feature selection (C = 0.15). A logistic regression algorithm was used to construct models based on each of the four sequences and a log-combined model was used to integrate the sequences. A receiver operating characteristic (ROC) curve was plotted to evaluate the model performance, and the Brier score was used to assess the overall accuracy of the model predictions.

RESULTS

The area under the ROC curve was 0.68, 0.73, 0.71, and 0.49 for Log-T1WI, Log-T2WI, Log-DWI, and Log-CE models, respectively, and 0.81 for the log-combined model. The accuracy, precision, sensitivity, and specificity of the log-combined model were 0.77, 0.88, 0.75, and 0.78, respectively. The best performance was obtained with the log-combined model with a Brier score of 0.18. Tumor location was identified as a significant clinical feature in comparison between the two groups (p < 0.05), and invasive pSPN was more frequent in the tail of the pancreas.

CONCLUSION

The log-combined model based on multiparametric MRI and clinical features can be used as a non-invasive diagnostic tool for preoperative prediction of pSPN invasive behavior and to facilitate the development of individualized treatment strategies and monitoring management plans.

Analysis of invasiveness and tumor-associated macrophages infiltration in solid pseudopapillary tumors of pancreas

BACKGROUND

Solid pseudopapillary tumor (SPT) is a rare pancreatic tumor. Considering its malignant behaviors, SPT has been classified as a low-grade malignant tumor. Indeed, only 9.2% of all SPT patients are initially diagnosed as malignant with invasion or metastasis. Thus, one of the challenges in managing SPT patients is predicting malignant behavior.

AIM

To investigate the malignant behavior and tumor-associated macrophage (TAM) infiltration between different histopathologic features of SPT patients.

METHODS

Twenty-five formalin-fixed paraffin-embedded tissue samples from 22 patients pathologically diagnosed with an SPT between 2009 and 2019 at West China Hospital were included in this retrospective study. Integrity of the capsule and growth pattern of the tumor cells was assessed microscopically in hematoxylin-eosin (HE)-stained sections. Based on the histopathological features, the SPT patients were divided into two groups: capsule or invasion. Clinical features, malignant behavior, and TAM infiltration were compared between the two groups.

RESULTS

Among the 22 SPT patients, 11 were identified for each group, having either a capsule or invasion histopathologic feature. Malignant behavior was more frequent in the invasion group, including 2 patients who had peripheral organ invasion, 3 with liver metastasis, and 1 with both lymph node and spleen metastases (P= 0.045). Ki-67 index of more than 3% was also more frequent in the invasion group (P = 0.045). Immunohistochemical analysis showed that the invasion group had a significant increase of CD68-positive TAMs in intratumor and peritumor sites in comparison with the capsule group (all P < 0.0001). Similarly, CD163-positive M2-like macrophages were also markedly increased in the intratumor and peritumor sites in the invasion group (all P < 0.0001). At the liver metastasis site, both intratumor and peritumor tissues showed relatively high-level CD68-positive TAMs and CD163-positive M2-like macrophages infiltration. However, the differences between the intratumor, peritumor and normal hepatic tissues did not reach statistical significance (all P > 0.05).

CONCLUSION

SPT patients with invasion evident under microscope were more likely to exhibit malignant behavior and TAM infiltration, especially M2-like macrophages. This finding can help in future investigations of the underlying mechanism of TAM-mediated SPT malignant behavior.

[Solid Pseudopapillary Neoplasm of the Pancreas in Children and Adolescents - Tailored Diagnostic and Operative Concepts in Four Patients]

BACKGROUND

Pancreatic tumors in children and adolescents are rare entities that can stay asymptomatic for long periods. They often become apparent as incidental findings or due to clinical symptoms, like abdominal pain. Solid pseudopapillary neoplasms of the pancreas (SPN) are rare representatives of this group, being low-grade malignant processes and requiring radical surgical treatment. We present four cases of SPN with different diagnostic and therapeutic approaches.

METHODS

A retrospective analysis of four cases of SPN treated between 2015 and 2020 was performed.

RESULTS

Four female patients (11-17 years) were found to have SPN during diagnostic procedures. Three of them were located in the pancreatic head. Histological confirmation was obtained with endosonographic-, CT-guided and open biopsy, respectively. R0 resection was achieved by a pylorus preserving, partial duodenopancreatectomy according to Traverso-Longmire. In one patient the tumor was located in the pancreatic tail with tumor adherence to the splenic vessels. A CT guided biopsy confirmed an SPN. A distal pancreatectomy and splenectomy was performed. Follow-up (6 months - 6 years) revealed no evidence of tumor recurrence, metastasis, or pancreoprive diabetes.

CONCLUSION

For the treatment plan preoperative histological confirmation of SPN is necessary. Based on the tailored diagnostic and operative concepts, treatment at a center with a specialized pediatric surgery, pediatric oncology, pediatric gastroenterology, pediatric radiology and pathology is mandatory.

How does the pancreatic solid pseudopapillary neoplasm confuse us: Analyzing from the point view of MRI-based radiomics?

OBJECTIVES

To construct MRI-based radiomics logistic model in differentiating solid pseudopapillary neoplasm (SPN) from three differential diseases containing adenocarcinoma, neuroendocrine tumor (NET), and cystadenoma of pancreas.

MATERIALS AND METHODS

A total of 21 SPNs and 140 differential diseases were enrolled. The MRI images of T1WI, T2WI, DWI, and contrast-enhanced (CE) sequences were taken to delineate the volume of interest, and the corresponding radiomics features were calculated. After the preprocess of data balance and image standardize, the data was divided into training set (6 SPNs and 42 differential diseases) and validation set (15 SPNs and 98 differential diseases) with a proportion of 7:3, randomly. Then after feature selection, four MRI-based logistic models included T1WI, T2WI, DWI, CE, and sum logistic models (Log-T1WI, Log-T2WI, Log-DWI, Log-CE, and Log-sum) were established. The receiver operation curve (ROC) was depicted to evaluate the efficacy of each model.

RESULTS

To the single MRI sequence, the AUCs of Log-T1WI, Log-T2WI, Log-DWI, and Log-CE were similar. Seemingly the AUCs of Log-T2WI were slightly higher with 0. 876 (95%CI, 0.797-0.956) in the training set and 0.853 (95%CI, 0.708-0.998) in the validation set. The Log-sum of four MRI sequences displayed better differentiating efficiency, with AUCs of 0.929 (95%CI, 0.877-0.980) in the training set and 0.925 (95%CI, 0.845-1.000) in the validation set. The Log-Ra/Clin model combined clinical information and radiomics showed the highest AUC of 0.962 (95%CI, 0.919-0.985).

CONCLUSIONS

MRI-based radiomics analysis helped to discern SPNs from radiologically misdiagnosed adenocarcinoma, neuroendocrine tumor, and cystadenoma of pancreas. The efficacy of single sequence logistic model was similar. The Log-sum combined four sequences and Log-Ra/Clin combined clinical information and radiomics demonstrated the better performance in distinction.

Surgical Resection of 78 Pancreatic Solid Pseudopapillary Tumors: a 30-Year Single Institutional Experience

BACKGROUND

Solid pseudopapillary tumors (SPTs) are rare, benign tumors of the pancreas that present as heterogeneous masses. We sought to evaluate the short- and long-term outcomes of surgical resected SPTs. Patients managed via initial surveillance were compared to those who underwent upfront resection.

METHODS

A prospectively maintained institutional database was used to identify patients who underwent surgical resection for a SPT between 1988 and 2018. Data on clinicopathological features and outcomes were collected and analyzed.

RESULTS

Seventy-eight patients underwent surgical resection for SPT during the study period. The mean age was 34.0 ± 14.6 years and a majority were female (N = 67, 85.9%) and white (N = 46, 58.9%). Thirty patients (37.9%) were diagnosed incidentally. Imaging-based presumed diagnosis was SPT in 49 patients (62.8%). A majority were located in the body or tail of the pancreas (N = 47, 60.3%), and 48 patients (61.5%) underwent a distal pancreatectomy. The median tumor size was 4.0 cm (IQR, 3.0-6.0), nodal disease was present in three patients (3.9%), and R0 resection was performed in all patients. No difference was observed in clinicopathological features and outcomes between patients who were initially managed via surveillance and those who underwent upfront resection. None of the patients under surveillance had nodal disease or metastasis at the time of resection; however, one of them developed recurrence of disease 95.1 months after resection. At a median follow-up of 36.1 months (IQR, 8.1-62.1), 77 (%) patients were alive and one patient (1.3%) had a recurrence of disease at 95.1 months after resection and subsequently died due to disease.

CONCLUSIONS

SPTs are rare pancreatic tumors that are diagnosed most frequently in young females. While a majority are benign and have an indolent course, malignant behavior has been observed. Surgical resection can result in exceptional outcomes.

Differentiation of aggressive from non-aggressive pancreatic solid pseudopapillary neoplasms using computed tomography

PURPOSES

Microscopic aggressive behaviors may be related with the prognosis of solid pseudopapillary neoplasms (SPNs). In this study, we investigate computed tomography (CT) features and differential diagnosis of aggressive and non-aggressive SPNs in pancreas.

MATERIALS AND METHODS

122 patients with pathologically proven SPNs in pancreas were included. Patients' age, tumor site, texture, shape, margins, exophytic growth, capsule, calcification, hemorrhage, pancreatic duct dilatation or pancreatic parenchyma atrophy, peripancreatic infiltration or metastases, vascular encasement, and enhancement pattern were assessed. The diagnostic accuracy was analyzed by using the receiver operating characteristic curve (ROC).

RESULTS

There were 30 aggressive SPNs and 92 non-aggressive SPNs. Aggressive SPNs showed significantly higher frequencies of an ill-defined margin, patient age > 40.5 years, and tumor size < 42.1 mm, but lower frequencies of complete capsule, hemorrhage compared with non-aggressive SPNs (p < 0.05). Lack of complete capsule and age > 40.5 years were independent risk factors of aggressive SPNs (odd ratio 7.08 and 3.1, respectively). When we applied the two predictors in the logistic regression model, the area under the curve (AUC) was 0.77 with sensitivity of 86.7% and specificity of 55.4%.

CONCLUSION

Size less than 42.1 mm, lack of complete capsule, ill-defined, and absent bleeding are useful CT imaging features for predicating aggressive SPNs. Patient age > 40.5 years and lack of complete capsule showed acceptable diagnostic performance for discriminating aggressive from non-aggressive SPNs.

Preoperative neutrophil-to-lymphocyte ratio predicts malignancy and recurrence-free survival of solid pseudopapillary tumor of the pancreas

BACKGROUND

Systemic inflammatory markers such as neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) have been shown to be prognostic for many types of pancreatic malignancy. The aim of this study was to evaluate the prognostic role of these markers in patients with solid pseudopapillary tumor of the pancreas (SPTP).

METHODS

Patients who underwent surgical resection for histologically confirmed SPTP were retrospectively reviewed in our institution. Preoperative NLR and PLR were calculated. Clinicopathologic data were correlated with the presence of malignant potential and recurrence-free survival (RFS).

RESULTS

A total of 113 patients with SPTP were included in this study. Of them, 23 were men and 90 were women, with a median age of 35 years (interquartile range, 25-44). The optimal cut-off values for malignant SPTP were 3.22 for NLR, and 75.5 for PLR, respectively. Univariate analysis showed that high NLR (>3.22) and white blood cell count more than 9.96 × 10⁹ /L were predictive of a malignant SPTP. Meanwhile, high NLR (P = 0.001) and age more than 35 years (P = 0.026) were associated with worse RFS. On multivariable analyses, high NLR was the only independent predictor of malignant SPTP (odd ratio 6.871; 95% confidence interval [CI], 1.482-31.864; P = 0.014) and RFS (hazard ratio 12.633; 95% CI, 1.758-90.790; P = 0.012).

CONCLUSIONS

This study highlights the supportive role of preoperative NLR in predicting malignancy and RFS of SPTP patients. Further studies including a larger cohort of patients are needed to corroborate our findings.

Prediction of malignancy and adverse outcome of solid pseudopapillary tumor of the pancreas

Since solid pseudopapillary tumor of the pancreas (SPTP) was officially classified by the World Health Organization in 1996, SPTP has recently received special attention in the literature. Studies have shown that SPTP is a heterogeneous tumor, with a small percentage of patients harboring aggressive behaviors. However, criteria for malignancy grade in SPTP have not been well established. The prognosis of SPTP is generally good, with cases having a chance for long-term survival even with recurrence and/or metastasis after surgical resection. The current American Joint Committee on Cancer/Union for International Cancer Control tumor, node, metastasis staging system is not specific to SPTP. The lack of a predictive staging classification that accurately describes the heterogeneity of this disease hinders meaningful research into optimal individualized therapy. Here we summarize and discuss the associated factors proposed for appraisal of the malignant potential and adverse outcome of SPTP.