Array comparative genomic hybridization analysis of solid pseudopapillary neoplasms of the pancreas

Pancreatic Solid Pseudopapillary Neoplasm: Key Pathologic and Genetic Features

CONTEXT.—

Solid pseudopapillary neoplasm of the pancreas is a low-grade malignant tumor generally associated with a good prognosis. Solid pseudopapillary neoplasms show peculiar morphologic features, but sometimes the differential diagnosis with other pancreatic neoplasms (ie, pancreatic neuroendocrine tumors) can be a challenging task, especially in cytologic or biopsy specimens. In these cases immunohistochemistry is a useful tool, but the diagnostic utility of several proposed immunohistochemical markers is questionable. In recent years, despite several attempts to characterize the pathogenetic, molecular, and prognostic features of solid pseudopapillary neoplasms, they still remain unclear.

OBJECTIVE.—

To give the reader a comprehensive update on this entity.

DATA SOURCES.—

The PubMed database (US National Library of Medicine) was searched using the following string: pseudopapillary tumor [AND/OR] neoplasm [AND/OR] pancreas. All articles written in English were included. In addition, because a heterogeneous terminology has been used in the past to define solid pseudopapillary neoplasms, the reference lists of each paper selected in the PubMed database were also reviewed.

CONCLUSIONS.—

This review gives a comprehensive update on the pathologic, clinical, and molecular features of solid pseudopapillary neoplasms, particularly addressing issues and challenges related to diagnosis. In addition, we have tried to correlate the molecular alterations with the morphologic and clinical features.

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

OBJECTIVE

The aim of the study was to assess the ability of contrast-enhanced computed tomography (CECT) to differentiate aggressive from nonaggressive solid pseudopapillary neoplasms (SPNs).

MATERIALS AND METHODS

Forty treatment-naive patients with pathologically proven pancreatic SPNs were included. Imaging characteristics were determined by consensus of 3 radiologists blinded to histopathologic aggressiveness. All patients underwent 4-phase CECT using a pancreatic protocol. The regions of interest of the tumor and the normal pancreas were documented on all phases. Lymph nodes were considered metastatic if greater than 1.0 cm in short-axis diameter.Fisher exact and Wilcoxon rank-sum tests were used to compare between aggressive and nonaggressive tumors.

RESULTS

No significant difference was noted between imaging covariates, such as internal hemorrhage, calcification, wall thickness perceptibility, vascular invasion, margins, cystic component, and pancreatic and biliary ductal dilation. Tumors with greater than 62.5 Hounsfield units and progressive enhancement during the delayed phase had aggressive characteristics (P = 0.03).

CONCLUSIONS

On delayed phase CECT, pathologically aggressive SPNs may show greater enhancement than nonaggressive SPNs.

Molecular Genetics of Pancreatic Neoplasms

Pancreatic neoplasms have a wide range of histologic types with distinct clinical outcomes. Recent advances in high-throughput sequencing technologies have greatly deepened our understanding of pancreatic neoplasms. Now, the exomes of major histologic types of pancreatic neoplasms have been sequenced, and their genetic landscapes have been revealed. This article reviews the molecular changes underlying pancreatic neoplasms, with a special focus on the genetic changes that characterize the histologic types of pancreatic neoplasms. Emphasis is also made on the molecular features of key genes that have the potential for therapeutic targets.

Recurrence of Solid Pseudopapillary Neoplasms of the Pancreas: Results of a Nationwide Study of Risk Factors and Treatment Modalities

BACKGROUND

Solid pseudopapillary neoplasms of the pancreas (SPPN) can relapse very late, but little is known about risk factors for recurrence and optimal treatment. We aimed to identify risk factors for recurrence and to analyze treatment modalities in all French pediatric cases of SPPN over the past 20 years.

MATERIAL AND METHODS

Data were collected from pediatric oncologists and surgeons, and also from adult pancreatic surgeons in order to identify late recurrences.

RESULTS

Fifty-one patients (41 girls) were identified. Median age at diagnosis was 13.1 years [8.7-17.9]. Abdominal pain was the commonest presenting symptom (32/49, 65%). The tumor was located in the pancreatic head in 24 patients (47%). Preoperative biopsy or cytology was performed in 14 cases (28%). All patients were operated with a median of 23 days [0-163] after diagnosis. The rate of postoperative morbidity was 29%. With a median follow-up of 65 months [0.3-221], the overall and event-free survival was 100% and 71%, respectively. Seven patients (13.7%) relapsed with a median of 43 months [33-94] after initial surgery. Six were treated surgically, either alone (n = 3) or with perioperative chemotherapy (n = 2) or hyperthermic intraperitoneal chemotherapy (n = 1). One patient in whom further treatment was not feasible was still alive at last news. Risk factors for recurrence were positive surgical margins (P = 0.03) and age less than 13.5 years at diagnosis (P = 0.03).

CONCLUSIONS

SPPN recurrence in this pediatric series was a rare and late event that did not undermine overall survival. Complete surgical removal of recurrent tumors appears to be the best option.

Diagnosis and molecular aspects of solid-pseudopapillary neoplasms of the pancreas

Solid-pseudopapillary neoplasm of the pancreas (SPN) is an uncommon low-grade malignant neoplasm occurring mostly in young women. In addition to its distinctive pathological appearance of pseudopapillae with poorly cohesive neoplastic cells, rare variants exist raising the differential diagnosis especially with neuroendocrine neoplasms. The overall prognosis for patients with SPNs is excellent after surgical resection. Nevertheless, 10% of cases may have malignant behavior characterized by tumor recurrence and/or metastasis. Despite numerous studies, the histogenesis of this neoplasm remains unclear. Distinctive molecular alterations such as the presence of CTNNB1 mutations are observed in nearly all cases, while mutations classically observed in ductal adenocarcinoma, such as KRAS, TP53, and SMAD4, are not observed in SPNs, reinforcing its distinct nature compared to all other pancreatic neoplasms. Recent transcriptional studies have shown that activation of the Wnt/beta-catenin pathway in these tumors is associated with the upregulation of genes belonging to Notch, Hedgehog, and androgen receptor signaling pathways.

Solid pseudopapillary neoplasm of the pancreas: clinicopathologic and survival analyses of 64 cases from a single institution

Although solid pseudopapillary neoplasms (SPNs) are considered tumors of low malignant potential, patients may present with aggressive disease (ie, liver metastasis/invasion into adjacent organs) and, rarely, die from disease. Although the clinicopathologic features associated with aggressive SPNs have been reported, important prognostic factors of survival remain unclear. We systematically reviewed 64 cases of SPN resected at our institution for tumor size, extent of invasion, margin status, presence of lymphovascular, muscular vessel, and perineural invasion, and lymph node and distant metastases. Clinicopathologic characteristics were correlated with the presence of metastasis/recurrence and disease-specific survival. Five (8%) patients presented with stage IV disease. During follow-up, 5 (13%) of 39 patients with stage I-II disease had recurrences. Patients with metastatic/recurrent SPNs had significantly larger tumor size (P<0.001) and more frequent tumor invasion into muscular vessels (P=0.02). In a median follow-up of 76 months, only 2 died of disease (1 who presented with extensive peritoneal tumor involvement who died 2.5 mo after surgery, and 1 unusual case who presented with multiple liver metastasis and peritoneal seeding who died 19 mo after surgery), and 5 were alive with disease. The 10-year disease-specific survival rate was 96%. Muscular vessel invasion (P=0.001), tumor (T) stage by European Neuroendocrine Tumors Society (ENETS) classification (P<0.001), ENETS stage grouping (P<0.001), and stage grouping by the American Joint Committee on Cancer (AJCC stage, P<0.001) were important predictors of disease-specific survival in patients with SPN. Our study highlights the importance of pathologic evaluation in risk assessment in patients with SPNs.

Clinical presentation and comparison of surgical outcome for segmental resection vs. Whipple's procedure for solid pseudopapillary tumor: Report of six new cases & literature review of 321 cases

AIM

Report 6 new cases of solid-pseudopapillary-pancreatic-tumor, comprehensively review 321 cases reported in American literature, and compare outcomes for segmental resection vs.. Whipple's procedure.

METHODS

Cases of solid-pseudopapillary-tumor at William Beaumont Hospital, 1999-2011, identified by computerized analysis of pathology reports. Comprehensive review of all American cases identified by computerized literature review. Segmental resection includes open/laparoscopic central pancreatectomy and anatomic distal pancreatectomy, but excludes enucleation.

RESULTS

Six cases of solid-pseudopapillary-pancreatic-tumors (0.5% of all solid pancreatic lesions), occurred during 1999-2011 at the hospital. Mean age at diagnosis = 27.7 years. All 6 were female. All patients had abdominal pain. Mean symptom duration = 10.0 days. All patients had normal routine blood tests. Mean APACHE II score at diagnosis = 1.8. All six patients had single heterogeneous lesions, with cystic/solid components. All patients underwent surgery: segmental resection-4, Whipple's procedure-2. Tumors were uniformly diagnosed by surgically resected tissue. Mean tumor size = 5.7 cm. Mean postoperative length of stay = 4.0 days for segmental resection (N = 4) vs. 14.0 days for Whipple's procedure (N = 2). All 6 patients are alive and well to-date, without evident local recurrence or metastasis. In a literature review, 45 patients undergoing Whipple's procedure versus 34 patients undergoing segmental resection, had significantly longer mean postoperative hospitalization (16.4 vs. 4.3 days, p = 0.01), and had increased unadjusted mortality (20.2% vs. 2.2%, p = 0.018). However, this mortality difference became insignificant when adjusting for longer mean follow-up of Whipple's procedure patients (Kaplan-Meier-survival-curve, p = 0.75).

CONCLUSIONS

This work suggests segmental resection of these pancreatic tumors localized to the body/tail may have a better surgical outcome than Whipple's procedure for tumors localized to the pancreatic head. Further studies are necessary.

Solid pseudopapillary tumor of the pancreas: the surgical procedures

PURPOSE

To evaluate the clinicopathological characteristics of solid pseudopapillary tumor and assess the curative effects of different procedures.

METHODS

A retrospective review was performed in 34 patients with this tumor surgically treated between January 2000 and June 2008. These patients were divided into minimized and standard resection groups. The clinical data of the two groups were analyzed.

RESULTS

Thirty-one females and three males were included in this study. There were no significant differences in age, blood glucose, hemoglobin, and albumin between the two groups. The surgical time for patients with a standard resection was longer (225 vs 124 min, P = 0.004), the transfusion rate was higher (52.6% vs 13.3%, P = 0.030), and the hospital stay was prolonged (21 vs 16 days, P = 0.034) in comparison to those who underwent a minimized resection. The complications rate in the standard resection group was higher than that in the minimized resection group, although no significant difference was found (42.1% vs 26.7%, P = 0.476). The long-term follow-up showed that all of the patients survived without recurrence except for one patient who died of other diseases 29 months after surgery.

CONCLUSION

A solid pseudopapillary tumor is a latent malignant tumor with excellent prognosis after its complete removal. When feasible, a minimized resection, such as enucleation and a segmental pancreatectomy, is a suitable approach, with excellent early and long-term results.

Solid-pseudopapillary neoplasm: a pancreatic enigma

Solid-pseudopapillary neoplasm of the pancreas is a relatively uncommon tumor. It typically affects young women, has nonspecific clinical and radiologic manifestations, and can be readily diagnosed by ultrasound-guided fine-needle aspiration and histopathologic evaluation. Histologic features characteristically show loosely cohesive, relatively uniform polygonal cells surrounding delicate capillary-sized blood vessels. Other features include cytoplasmic vacuolization, finely stippled chromatin, nuclear grooving, eosinophilic hyaline globules, and degenerative changes. Almost all solid-pseudopapillary neoplasms harbor mutations in the beta-catenin gene. They stain with beta-catenin, CD10, and focally with neuroendocrine markers. Although previously considered benign, this tumor is currently considered a low-grade malignant epithelial neoplasm with low metastatic rate and high overall survival. Most patients are cured by complete surgical excision. Despite the characterization of the morphologic and molecular features of this enigmatic neoplasm, more work is needed to uncover its cell of origin and true histogenesis.

Solid pseudopapillary neoplasms of the pancreas

SPN is a rare neoplasm that affects mainly young women. Despite this feature, SPN have been seen in both genders, multiple races, and at a wide range of ages. The genetic mechanism behind the development of SPN is distinct from the more lethal ductal carcinoma of the pancreas. This difference is reflected in the favorable outcome for patients with SPN. Surgery is typically curative in patents with localized disease and possibly in patients with limited metastasis or local extension. No consensus exists on an effective systemic therapy. There are no reliable predictors for disease-specific mortality or recurrence in the minority of patients who develop aggressive disease.