Clinicopathological analysis of β-catenin and Axin-1 in solid pseudopapillary neoplasms of the pancreas

The scaffold protein AXIN1: gene ontology, signal network, and physiological function

AXIN1, has been initially identified as a prominent antagonist within the WNT/β-catenin signaling pathway, and subsequently unveiled its integral involvement across a diverse spectrum of signaling cascades. These encompass the WNT/β-catenin, Hippo, TGFβ, AMPK, mTOR, MAPK, and antioxidant signaling pathways. The versatile engagement of AXIN1 underscores its pivotal role in the modulation of developmental biological signaling, maintenance of metabolic homeostasis, and coordination of cellular stress responses. The multifaceted functionalities of AXIN1 render it as a compelling candidate for targeted intervention in the realms of degenerative pathologies, systemic metabolic disorders, cancer therapeutics, and anti-aging strategies. This review provides an intricate exploration of the mechanisms governing mammalian AXIN1 gene expression and protein turnover since its initial discovery, while also elucidating its significance in the regulation of signaling pathways, tissue development, and carcinogenesis. Furthermore, we have introduced the innovative concept of the AXIN1-Associated Phosphokinase Complex (AAPC), where the scaffold protein AXIN1 assumes a pivotal role in orchestrating site-specific phosphorylation modifications through interactions with various phosphokinases and their respective substrates.

Solid pseudopapillary neoplasm of the pancreas with multiple liver metastases successfully managed with staged resection

Due to the rarity of the disease, there are no guidelines or consensus for the management of solid pseudopapillary neoplasm of the pancreas with liver metastasis. We describe a patient with solid pseudopapillary neoplasm of the pancreas with multiple liver metastases who was successfully managed with staged resection. A previously healthy 50-year-old female presented to the clinic with dull epigastric pain. The contrast-enhanced computed tomography showed a well-defined cystic lesion at the distal body and tail of the pancreas with multiple liver deposits. A core needle liver biopsy was suspicious of a hepatic epithelioid hemangioendothelioma. A distal pancreatectomy with splenectomy and a left hemi-hepatectomy were performed with a subsequent staged right posterior sectionectomy to address the inadequate future liver remnant. The final histology with immunohistochemistry revealed a pancreatic solid pseudopapillary neoplasm. The patient had satisfactory surgical and oncological outcomes with no recurrence. As these are slow growing tumours, appropriately spaced staged liver resection was feasible to allow hypertrophy of the liver remnant and physiological recovery of the patient. The discrepancy in the histology and cross-sectional imaging led to a pre-operative diagnostic dilemma, and the final diagnosis was reached after surgical resection. Thus, resectable metastatic solid pseudopapillary neoplasm of the pancreas may be offered a primary curative radical surgery before considering other treatment modalities.

Clinical characteristics, treatment outcomes, and occurrence of diabetes mellitus after pancreatic resection of solid pseudopapillary tumor in children and adolescents: A single institution experience with 51 cases

BACKGROUND

Solid pseudopapillary tumors (SPTs) are rare, but they comprise the majority of pediatric pancreatic neoplasms. However, studies on these conditions in pediatric patients are lacking. The aim of this study was to investigate the clinical characteristics and treatment outcomes in children and adolescents with SPTs.

METHODS

This retrospective study included 51 patients with SPTs who had undergone pancreatic tumor resection before the age of 19 years at Samsung Medical Center in Korea (from November 1994 to August 2020). We investigated the postoperative outcomes.

RESULTS

Of the 51 patients with SPTs (female, 88.2%), the median age at diagnosis was 14 years (range, 8-19). The most common symptom was abdominal pain (60.8%), and 14 patients (27.5%) were asymptomatic. The median maximal tumor diameter was 7 cm (range, 1.4-14), and the pancreatic body and/or tail were involved in 68.6% of patients. The short-term complication rate was 21.5%, and the recurrence rate was 5.9%. New-onset diabetes mellitus (NODM) occurred in four patients.

CONCLUSIONS

The ideal treatment for SPTs is complete resection of the tumor; however, long-term postoperative complications including NODM should be monitored carefully, particularly in children and adolescents.

Targeted next generation sequencing of pancreatic solid pseudopapillary neoplasms show mutations in Wnt signaling pathway genes

Solid pseudopapillary neoplasms of the pancreas are rare neoplasms that have been shown to harbor recurrent somatic pathogenic variants in the beta-catenin gene, CTNNB1. Here, we used targeted next generation sequencing to analyze these tumors for other associated mutations. Six cases of solid pseudopapillary neoplasms were studied. DNA extracted from formalin-fixed paraffin embedded tissue blocks was analyzed using the Ion Torrent platform, with the 50-gene Ampliseq Cancer Hotspot Panel v2 (CHPv2), with further variant validation performed by Sanger sequencing. Four tumors (67%) were confirmed to harbor mutations within CTNNB1, two with c.109T > G p.(Ser37Ala) and two with c.94G > A p.(Asp32Asn). One case showed a frameshift deletion in the Adenomatous Polyposis Coli gene, APC c.3964delG p.(Glu1322Lysfs*93) with a variant allele frequency of 42.6%. Sanger sequencing on non-tumoral tissue confirmed the variant was somatic. The patient with the APC mutation developed metastasis and died. In addition to the four cases harboring CTNNB1 variants, we found a case characterized by poor outcome, showing a rare frameshift deletion in the APC gene. Since the APC product interacts with beta-catenin, APC variants may, in addition to CTNNB1, contribute to the pathogenesis of solid pseudopapillary neoplasms via the Wnt signaling pathway.

Molecular dynamic simulation of mutated β-catenin in solid pseudopapillary neoplasia of the pancreas

Solid pseudopapillary neoplasia of the pancreas (SPN) is a rare pancreatic neoplasm that frequently harbors mutations in catenin β1 (CTNNB1, encoding β-catenin) as a part of its molecular pathogenesis. Mutations to CTNNB1 reported in SPN usually occur at the serine/threonine phosphorylation sites, including codons 33, 37 and 41, and the flanking residues of codon 33. On analysis of 3 cases of SPN, mutations to CTNNB1 were detected in codon 32 (D32A and D32Y). As this residue, aspartic acid, is not a direct phosphorylation site of the protein, molecular modeling tools were used to predict the influence of these mutations on the protein structure of β-catenin. A total of three MD simulations (wild-type, D32A, and D32Y) were performed to visualize the conformations of β-catenin under in vivo, aqueous-phase conditions at 37°C. In the wild-type protein, the secondary structure of residues P16-H28 remained helical; we therefore hypothesized that the helical structure of this protein fragment (residues M11-G50) was necessary for phosphorylation of S33 phosphorylation. The loss of the secondary structure in P16-H28 was observed in D32A, losing its helical structure and becoming a turn; however, in the D32Y mutant, the helical structure remained. The present demonstrated that structural changes in the mutated β-catenin protein at D32 could potentially explain the mechanism behind its defective phosphorylation in the pathogenesis of SPN.

Overexpression of SOX11 and TFE3 in Solid-Pseudopapillary Neoplasms of the Pancreas

OBJECTIVES

To characterize the expression of SOX11 and TFE3 proteins in solid-pseudopapillary neoplasms (SPNs) and their histologic mimickers.

METHODS

Immunohistochemistry for SOX11, TFE3, and β-catenin was performed on 31 cases of surgically resected SPNs. Neuroendocrine tumors, acinar cell carcinomas, and pancreatoblastomas served as controls.

RESULTS

Nuclear immunoreactivity for SOX11 was detected in all SPNs and five of 31 control tumors. Nuclear immunoreactivity for TFE3 was detected in 30 SPNs and three control tumors. Nuclear immunoreactivity for β-catenin was detected in all SPNs and four control tumors. The combination of three markers as immunohistochemical panels resulted in optimal sensitivity and specificity.

CONCLUSIONS

Both SOX11 and TFE3 were overexpressed in SPNs and may be involved in the pathogenesis. Clinically, SOX11 and TFE3 can be potentially used as diagnostic markers in distinguishing indeterminate SPNs from their histologic mimickers.

Solid pseudopapillary tumor of the pancreas: clinical-pathological features and management of 13 cases

Background and aim

Solid pseudopapillary tumor (SPT) of the pancreas is a rare pathological condition, representing less than 3% of all exocrine pancreatic tumors. SPT usually occurs in young females, without notable symptoms, with a low malignant potential and excellent prognosis.

Method

We conducted a retrospective study during the period January 2005 – January 2015. SPT patients admitted in our institution were reviewed by describing demographic data, clinico-pathologic and radiological features, therapeutic management and prognosis records.

Results

Thirteen patients with SPT were identified (10 females), with a median age of 30 years. The main clinical presentation was abdominal pain (92.3%). The tumor was mostly located in the body or tail of the pancreas (77%), and the mean size was 8.2 cm. Regarding the surgical approach there were 5 distal pancreatectomies with splenectomy, 3 body and tail pancreatectomies, 2 body and tail pancreatectomies with splenectomy, 2 pancreato-duodenectomy, 1 partial enucleation and of all only 2 partial resections. Postoperative hematoxylin- eosin staining and immunohistochemistry confirmed the diagnosis in all cases. None of the patients had lymph nodes metastases. Only one local invasion. There was one case of death due to postoperative complications. Four cases followed adjuvant systemic chemotherapy. The mean follow-up was 18 months, without evidence of recurrence during this period.

Conclusion

SPT should always be considered in the differential diagnosis in young women with a pancreatic tumor. Complete surgical excision is the treatment of choice, and is usually curative. The decision to administer systemic therapy must be individualized. Malignant behavior and late recurrences mandates long-term follow-up for patients with SPT.

Somatic Genetic Variation in Solid Pseudopapillary Tumor of the Pancreas by Whole Exome Sequencing

Solid pseudopapillary tumor of the pancreas (SPT) is a rare pancreatic disease with a unique clinical manifestation. Although CTNNB1 gene mutations had been universally reported, genetic variation profiles of SPT are largely unidentified. We conducted whole exome sequencing in nine SPT patients to probe the SPT-specific insertions and deletions (indels) and single nucleotide polymorphisms (SNPs). In total, 54 SNPs and 41 indels of prominent variations were demonstrated through parallel exome sequencing. We detected that CTNNB1 mutations presented throughout all patients studied (100%), and a higher count of SNPs was particularly detected in patients with older age, larger tumor, and metastatic disease. By aggregating 95 detected variation events and viewing the interconnections among each of the genes with variations, CTNNB1 was identified as the core portion in the network, which might collaborate with other events such as variations of USP9X, EP400, HTT, MED12, and PKD1 to regulate tumorigenesis. Pathway analysis showed that the events involved in other cancers had the potential to influence the progression of the SNPs count. Our study revealed an insight into the variation of the gene encoding region underlying solid-pseudopapillary neoplasm tumorigenesis. The detection of these variations might partly reflect the potential molecular mechanism.

Pancreatic desmoid-type fibromatosis with beta-catenin gene mutation-Report of a case and review of the literature

We experienced a rare case of pancreatic desmoid-type fibromatosis (DTF) in a 75-year-old Japanese woman. She was asymptomatic but routine examination including ultrasonography revealed a mass in the abdomen. For precise examination, she was referred to the regional hospital. Computed tomography showed that the mass was protruding anteriorly from the left-sided pancreas. Because of the enlargement of the mass lesion, distal pancreatectomy with splenectomy was performed after about 3 months. Macroscopically, the mass was encapsulated and approximately 8cm in diameter. Histological examination revealed that spindle or blunt stellate cells were proliferating in parallel or storiform fashion with myxoid and fibrous background. The tumor cells did not show prominent atypia and mitoses were rarely seen, suggesting that the tumor was low grade or borderline. Immunohistochemistry showed obvious nuclear staining of beta-catenin. Furthermore, analysis of beta-catenin gene revealed that the tumor had a typical missense mutation of threonine to alanine at colon 41 (T41A) in exon 3. These findings confirmed the pathological diagnosis of DTF of the pancreas. To the best of our knowledge, 18 cases of pancreatic DTF have been reported in the English literature and beta-catenin gene mutation had been examined in only one case among them. Thus, our case is the 19th pancreatic DTF and the second case with confirmed beta-catenin gene mutation.

Genomic and immunohistochemical analysis in human adrenal cortical neoplasia reveal beta-catenin mutations as potential prognostic biomarker

Evaluation for malignancy of the adrenal cortex, adrenal cortical carcinoma (ACC), is a challenge in surgical pathology due to its relative rarity and histologic overlap with its benign counterpart, adrenocortical adenoma (ACA). We characterized a cohort of human ACC and ACA, including a molecular screen, with a goal of identifying potential diagnostic adjuncts. Thirty-six cases of ACC underwent histologic and clinical review. In the 31 ACC cases with available material and a cohort of 10 ACA cases, a multiplex nucleotide amplification molecular screen from formalin-fixed, paraffin-embedded tissue was peformed. ACCs demonstrated a wide variety of clinical and histologic characteristics with overall poor but unpredictable survival for subjects with ACC. By mutational screen, 12/31 (38.7%) carcinomas harbored CTNNB1 mutations, 1 with an additional TP53 mutation; 1 case each had isolated APC and TP53 mutations; 16 were wild-type for all tested loci; and 1 case demonstrated repeated assay failures. Two of the 10 ACA (20%) demonstrated CTNNB1 mutations by mutational screen, with no additional mutations. Immunohistochemistry for beta-catenin was performed and compared with the results of the molecular screen. Strong nuclear beta-catenin immunopositivity corresponded to the presence of CTNNB1 mutation by genotyping in 10 of 12 cases (83% sensitivity); the mismatched case(s) demonstrated strong membranous staining by immunohistochemistry. Seventeen of the 18 cases without CTNNB1 mutation showed membranous staining or did not stain (94% specificity); the mismatched case demonstrated scattered (<10%) positive nuclei. Both mutations in ACA were corroborated with immunohistochemistry for beta-catenin. No histomorphologic parameter appeared dominant in lesions with a particular mutational status. Based on these results, mutational status of CTNNB1 in adrenal cortical neoplasms can be predicted with reasonable accuracy by immunohistochemical cellular localization. Nuclear localization of beta-catenin by immunostain may be helpful in analysis of select lesions of the adrenal cortex whose biological behavior is uncertain from clinical and histologic information; a larger cohort is required to test this hypothesis.

CTNNB1 mutational analysis of solid-pseudopapillary neoplasms of the pancreas using endoscopic ultrasound-guided fine-needle aspiration and next-generation deep sequencing

BACKGROUND

Solid-pseudopapillary neoplasm (SPN), a rare neoplasm of the pancreas, frequently harbors mutations in exon 3 of the cadherin-associated protein beta 1 (CTNNB1) gene. Here, we analyzed SPN tissue for CTNNB1 mutations by deep sequencing using next-generation sequencing (NGS).

METHODS

Tissue samples from 7 SPNs and 31 other pancreatic lesions (16 pancreatic ductal adenocarcinomas (PDAC), 11 pancreatic neuroendocrine tumors (PNET), 1 acinar cell carcinoma, 1 autoimmune pancreatitis lesion, and 2 focal pancreatitis lesions) were analyzed by NGS for mutations in exon 3 of CTNNB1.

RESULTS

A single-base-pair missense mutations in exon 3 of CTNNB1 was observed in all 7 SPNs and in 1 of 11 PNET samples. However, mutations were not observed in the tissue samples of any of the 16 PDAC or other four pancreatic disease cases. The variant frequency of CTNNB1 ranged from 5.4 to 48.8 %.

CONCLUSIONS

Mutational analysis of CTNNB1 by NGS is feasible and was achieved using SPN samples obtained by endoscopic ultrasound-guided fine needle aspiration.

Utilization of ancillary studies in the cytologic diagnosis of biliary and pancreatic lesions: The Papanicolaou Society of Cytopathology Guidelines

The Papanicolaou Society of Cytopathology has developed a set of guidelines for pancreatobiliary cytology including indications for endoscopic ultrasound guided fine needle aspiration, terminology and nomenclature of pancreatobiliary disease, ancillary testing and post-biopsy management. All documents are based on the expertise of the authors, a review of the literature, discussion of the draft document at several national and international meetings and synthesis of selected online comments of the draft document. This document presents the results of these discussions regarding the use of ancillary testing in the cytologic diagnosis of biliary and pancreatic lesions. Currently, fluorescence in-situ hybridization (FISH) appears to be the most clinically relevant ancillary technique for cytology of bile duct strictures. The addition of FISH analysis to routine cytologic evaluation appears to yield the highest sensitivity without loss in specificity. Loss of immunohistochemical staining for the protein product of the SMAD4 gene and positive staining for mesothelin support a diagnosis of ductal adenocarcinoma. Immunohistochemical markers for endocrine and exocrine differentiation are sufficient for a diagnosis of endocrine and acinar tumors. Nuclear staining for beta-catenin supports a diagnosis of solid-pseudopapillary neoplasm. Cyst fluid analysis for amylase and carcinoembryonic antigen aids in the pre-operative classification of pancreatic cysts. A number of gene mutations (KRAS, GNAS, von Hippel-Lindau, RNF43 and CTNNB1) may be of aid in the diagnosis of cystic neoplasms. Other ancillary techniques do not appear to improve diagnostic sensitivity sufficiently to justify their increased costs.

Guidelines for pancreaticobiliary cytology from the Papanicolaou Society of Cytopathology: A review

The newest installment on state-of-the-art standards of practice in cytopathology from the Papanicolaou Society of Cytopathology (PSC) focuses on the pancreaticobiliary system. Similar to the National Cancer Institute recommendations for aspiration cytology of the thyroid, the PSC guidelines for pancreaticobiliary cytology addresses indications, techniques, terminology and nomenclature, ancillary studies, and postprocedure management. Each committee was composed of a multidisciplinary group of experts in diagnosing, managing, and treating patients with pancreaticobiliary disease. Draft documents were posted on an interactive Web-based forum hosted by the PSC Web site (www.papsociety.org) and the topics of terminology, ancillary testing, and management were presented at national and international meetings over an 18-month period for discussion and feedback from practicing pathologists around the world. This review provides a synopsis of these guidelines.

Utilization of ancillary studies in the cytologic diagnosis of biliary and pancreatic lesions: the Papanicolaou Society of Cytopathology guidelines for pancreatobiliary cytology

The Papanicolaou Society of Cytopathology has developed a set of guidelines for pancreatobiliary cytology including indications for endoscopic ultrasound-guided fine-needle aspiration, terminology and nomenclature of pancreatobiliary disease, ancillary testing, and post-biopsy management. All documents are based on the expertise of the authors, a review of the literature, discussions of the draft document at several national and international meetings, and synthesis of selected online comments of the draft document. This document presents the results of these discussions regarding the use of ancillary testing in the cytologic diagnosis of biliary and pancreatic lesions. Currently, fluorescence in situ hybridization (FISH) appears to be the most clinically relevant ancillary technique for cytology of bile duct strictures. The addition of FISH analysis to routine cytologic evaluation appears to yield the highest sensitivity without loss in specificity. Loss of immunohistochemical staining for the protein product of the SMAD4 gene and positive staining for mesothelin support a diagnosis of ductal adenocarcinoma. Immunohistochemical markers for endocrine and exocrine differentiation are sufficient for a diagnosis of endocrine and acinar tumors. Nuclear staining for beta-catenin supports a diagnosis of solid-pseudopapilary neoplasm. Cyst fluid analysis for amylase and carcinoembryonic antigen aids in the preoperative classification of pancreatic cysts. Many gene mutations (KRAS, GNAS, VHL, RNF43, and CTNNB1) may be of aid in the diagnosis of cystic neoplasms. Other ancillary techniques do not appear to improve diagnostic sensitivity sufficiently to justify their increased costs.

β-catenin is a valuable marker for differential diagnosis of osteoblastoma and osteosarcoma

Osteoblastoma (OB) and osteosarcoma (OS) are 2 bone tumors that predominantly affect young adults. The clinical management of OS differs significantly from that of OB, and thus, accurate diagnosis of OB and OS is critical in determining appropriate treatment modality. However, in certain cases, OS significantly overlaps with OB in clinical and radiographic characteristics, and therefore, the differential diagnosis of OB and OS can be difficult, especially when biopsy material is insufficient. To date, there have been few reports on markers for differential diagnosis of OB and OS. We have previously shown that the Wnt/β-catenin pathway is inactivated in OS. In this study, we aimed to investigate whether the cellular distribution pattern of β-catenin is a potential marker for the differential diagnosis of OB and OS. Immunohistochemical staining was studied in 17 OB samples (21 biopsies; 17 primary and 4 recurrent) and 37 OS samples with complete follow-up information. Moderate-to-strong nuclear β-catenin staining was found in all OB specimens (17/17). In contrast, positive staining of β-catenin was found in the cytoplasm and/or membrane but not the nucleus in all 32 cases of nonchondroblastic OS (32/32) and the classic OS component in chondroblastic OS (5/5). The only positive nuclear β-catenin staining detected in OS biopsies was in chondroblastic OS cells (5/5). In summary, our results indicate that, in addition to conventional histopathologic evaluation, cellular distribution of β-catenin may be used as a valuable marker in the differential diagnosis of OB and OS. Nuclear β-catenin staining strongly suggests OB, whereas cytoplasmic/membranous staining of β-catenin suggests OS.

Solid pseudopapillary tumor of the pancreas in children: 15-year experience at a single institution with assays using an immunohistochemical panel

PURPOSE

The aim of this study was to analyze the clinicopathological characteristics of solid pseudopapillary tumor (SPT) of the pancreas and to utilize an immunohistochemical panel to identify specific markers of the disease.

METHODS

Eleven patients diagnosed with and treated for SPT of the pancreas over the past 15 years were retrospectively analyzed.

RESULTS

The 11 patients consisted of 8 females and 3 males, of mean age at operation of 13.5 years (range, 10 to 18 years). The most frequent presenting symptom was abdominal pain and/or mass. One patient was referred with hemoperitoneum due to traumatic tumor rupture. The lesions were located in the body, head and tail of the pancreas in four, four, and three patients, respectively. Mean tumor diameter was 7.9 cm (range, 2.5 to 15 cm). Surgical procedures included distal pancreatectomy with splenectomy in four patients, pylorus preserving pancreaticoduodenectomy in four, distal pancreatectomy in two, and subtotal pancreatectomy with splenectomy in one. Mean follow-up was 60.5 months (range, 15 to 126 months). All patients remain alive without tumor recurrence. Immunohistochemical staining showed that all tumors were positive for β-catenin, progesterone receptor (PR), vimentin, and CD99. However, all tumors were negative for E-cadherin and cytokeratin 7 expression.

CONCLUSION

Patients with SPT of the pancreas have an excellent prognosis after surgical excision. Immunohistochemically, E-cadherin/β-catenin, PR, vimentin, and CD99 would help establish the diagnosis of SPT of the pancreas, although the results of immunohistochemical staining were found to have an indistinct complex immunoprofile.

Solid pseudopapillary tumor of the pancreas and concomitant urogenital malformations in a young woman

Abstract

Solid pseudopapillary tumor (SPT) of the pancreas is a rare pancreatic tumor with low malignant potential. It occurs characteristically more often in young women. SPT associated with extra- and pancreatic anomalies are occasionally reported. Here we report a case of pancreatic SPT with concomitant urogenital malformations including solitary kidney and uterus didelphys in a 25-year-old woman. The patient underwent central pancreatectomy, and SPT was confirmed with pathological results. Recurrence or metastasis was not found after 14 months of follow-up.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/4264758678755142

Large solid-pseudopapillary neoplasm of the pancreas with aberrant protein expression and mutation of β-catenin: a case report and literature review of the distribution of β-catenin mutation

Solid-pseudopapillary neoplasms (SPN) are rare pancreatic tumors. The etiology of SPN involves mutations in the gene that encodes β-catenin (CTNNB1). We herein report the case of a 23-year-old woman with a large SPN with proliferating tumor cells that displayed both solid and pseudo-papillary patterns. The simultaneous nuclear accumulation and loss of membrane localization of β-catenin and E-cadherin was specifically observed in the tumor cells. Further, the tumor cells were shown to harbor a missense mutation in exon 3 of CTNNB1. We also present a review of the literature describing the clustering of CTNNB1 mutations in patients with SPN.

Solid pseudopapillary tumor of the pancreas: a single-institution 20-year series of pediatric patients

PURPOSE

Solid pseudopapillary tumor (SPT) of the pancreas is a rare neoplasm. The objective of this study was to review our institution's experience and provide an update on current management in the pediatric population.

METHODS

Our pathology database identified all patients with SPT for a 20-year period (1991-2011). Demographics, clinical characteristics, operative details, pathology, and outcomes data were retrospectively reviewed.

RESULTS

Eleven patients with SPT were identified. Most were female and Hispanic. Median age at resection was 14 years (9-17 years). Most patients presented with abdominal pain. Diagnostic imaging was most commonly an ultrasound or computed tomography. All tumors were resected en bloc. Median greatest tumor diameter was 5 cm (3.5-12 cm). Median length of stay was 8 days (5-19 days). Complications included pancreatic leak, chyle leak, delayed gastric emptying, fat malabsorption, and incisional keloid. Recurrence developed after 2.5 years in 1 patient with positive surgical margins. There were no metastases or deaths. Median follow-up was 1.4 years (0.6-5.9 years).

CONCLUSION

This pediatric series of SPT from a single institution corroborates previous reports in the literature. In our experience, SPT behaves like a low-grade malignancy and has an excellent prognosis. Surgical resection is dictated by tumor location and remains the treatment of choice.