Gastrointestinal Tract Granular Cell Tumor in the Pediatric Population: A Multicenter Experience

BACKGROUND

Pediatric granular cell tumors (GCT) involving the gastrointestinal tract (GIT) are rare with limited case report/series reported to date.

METHODS

Multicenter retrospective study of pediatric GIT GCT.

RESULTS

A total of 10 cases were included in the study with a median age of 13.5 years (range: 7-18 years) and were predominantly female patients (60%). In half of the patients no significant medical history was present with the remaining 5 having Crohn disease (10%), eosinophilic esophagitis (EoE) (10%), Crohn disease and EoE (10%), growth hormone deficiency (10%), and aplasia cutis congenita (10%). The GCT median size was 1.3 cm (range: 1-1.6 cm) and were more commonly located in the esophagus (70%) followed by the stomach (20%) and rectum (10%). Most of the cases showed round/polygonal tumor cells with abundant granular cytoplasm, and none of the cases had nuclear atypia, increased mitotic activity, or tumor cell necrosis. None of our cases received specific therapy for GCT other than clinical follow-up, and none of the patients had evidence of local recurrence or metastatic disease.

CONCLUSION

We present our multicenter experience with GIT GCT, all cases had a benign course. Interestingly, 4 of the esophageal GCT cases (including 2 patients with EoE) showed an eosinophil-rich esophagitis in the underlying mucosa.

The Pathologic Diagnosis of Pediatric Soft Tissue Tumors in the Era of Molecular Medicine: The Sarcoma Pediatric Pathology Research Interest Group Perspective

CONTEXT.—

Pediatric soft tissue tumors are one of the areas of pediatric pathology that frequently generate consult requests. Evolving classification systems, ancillary testing methods, new treatment options, research enrollment opportunities, and tissue archival processes create additional complexity in handling these unique specimens. Pathologists are at the heart of this critical decision-making, balancing responsibilities to consider expediency, accessibility, and cost-effectiveness of ancillary testing during pathologic examination and reporting.

OBJECTIVE.—

To provide a practical approach to handling pediatric soft tissue tumor specimens, including volume considerations, immunohistochemical staining panel recommendations, genetic and molecular testing approaches, and other processes that impact the quality and efficiency of tumor tissue triage.

DATA SOURCES.—

The World Health Organization Classification of Soft Tissue and Bone Tumors, 5th edition, other recent literature investigating tissue handling, and the collective clinical experience of the group are used in this manuscript.

CONCLUSIONS.—

Pediatric soft tissue tumors can be difficult to diagnose, and evaluation can be improved by adopting a thoughtful, algorithmic approach to maximize available tissue and minimize time to diagnosis.

A Novel Tissue-Free Method to Estimate Tumor-Derived Cell-Free DNA Quantity Using Tumor Methylation Patterns

Estimating the abundance of cell-free DNA (cfDNA) fragments shed from a tumor (i.e., circulating tumor DNA (ctDNA)) can approximate tumor burden, which has numerous clinical applications. We derived a novel, broadly applicable statistical method to quantify cancer-indicative methylation patterns within cfDNA to estimate ctDNA abundance, even at low levels. Our algorithm identified differentially methylated regions (DMRs) between a reference database of cancer tissue biopsy samples and cfDNA from individuals without cancer. Then, without utilizing matched tissue biopsy, counts of fragments matching the cancer-indicative hyper/hypo-methylated patterns within DMRs were used to determine a tumor methylated fraction (TMeF; a methylation-based quantification of the circulating tumor allele fraction and estimate of ctDNA abundance) for plasma samples. TMeF and small variant allele fraction (SVAF) estimates of the same cancer plasma samples were correlated (Spearman's correlation coefficient: 0.73), and synthetic dilutions to expected TMeF of 10-3 and 10-4 had estimated TMeF within two-fold for 95% and 77% of samples, respectively. TMeF increased with cancer stage and tumor size and inversely correlated with survival probability. Therefore, tumor-derived fragments in the cfDNA of patients with cancer can be leveraged to estimate ctDNA abundance without the need for a tumor biopsy, which may provide non-invasive clinical approximations of tumor burden.

ALK-Rearranged Epithelioid Mesenchymal Neoplasm: Expanding the Spectrum of Tyrosine Kinase-Altered Mesenchymal Tumors

The anaplastic lymphoma kinase (ALK) gene encodes a receptor tyrosine kinase, and fusions involving this gene have been reported in a variety of mesenchymal neoplasms. ALK-altered tumors with epithelioid morphology have been described in epithelioid inflammatory myofibroblastic sarcoma and epithelioid fibrous histiocytoma. Herein, we describe the clinicopathologic features of 7 ALK-rearranged mesenchymal tumors with epithelioid morphology occurring predominately in the pediatric population. Tumors occurred in 4 females and 3 males with an age ranging from 1 month to 28 years. Five tumors were superficial and solitary, while 1 presented with multiple peritoneal/omental nodules, and 1 presented as a large mediastinal mass. Morphologically, all tumors comprised epithelioid cells arranged in sheets, anastomosing cords, or small clusters embedded in a myxohyaline stroma. The cells had slightly variably sized ovoid nuclei with moderately prominent nucleoli and abundant eosinophilic cytoplasm. Four cases had sparse mitotic figures without necrosis. The remaining 3 tumors (2 deep and 1 superficial) had more than 10 mitoses per 10 high-power fields as well as foci of necrosis. ALK fusions were identified in all cases. The fusion partners included HMBOX1 (n = 1), VCL (n = 1), PRRC2B (n = 1), MYH10 (n = 1), STRN (n = 1), and EML4 (n = 2). One tumor recurred locally 2 years after initial resection; 1 patient had widely metastatic disease (mediastinal tumor). At the time of last follow-up (n = 6), 4 patients were alive without evidence of disease, 1 died due to complications of therapy (peritoneal tumor), and 1 was alive with disease. Our findings expand the spectrum of ALK-rearranged mesenchymal tumors. Our cases predominately occurred in older children and mainly exhibited epithelioid to round cell morphology, as opposed to spindle cell morphology. We also show that tumors in a deep location with higher-grade features follow a more aggressive clinical course.

Comparison of urine cell-free DNA with blood-based screening for detection of bladder cancer

457

Background: Plasma cell-free DNA (pcfDNA) has shown great promise for non-invasive, multi-cancer early detection (MCED), but has lower sensitivity for early-stage urological cancers due to low tumor fraction in plasma. Urine cfDNA (ucfDNA) has the potential to improve detection and monitoring of early-stage urological cancers due to its proximity to the affected organs and ease of collection. We conducted an exploratory study to assess the utility of methylation patterns in ucfDNA to detect BC in patients with suspicious bladder lesions, and compare to detection using matched pcfDNA. Methods: Urine and blood were collected from patients with suspicion of new (N=17) or recurrent (N=20) non-muscle invasive BC (NMIBC), and from non-cancer (NC) patients with urological conditions (N=16). Patients with suspicion of NMIBC were diagnosed and staged by transurethral resection of bladder tumor (TURBT) and conventional imaging. Tumor allele fraction (TAF) estimates from ucfDNA were inferred using a method trained on methylation patterns enriched in BC tissue (N=49) relative to an external reference dataset of NC ucfDNA (N=176). We set a detection threshold, using a maximum TAF value from a separate set of NC urine samples (N=50), to determine ucfDNA sensitivity for detecting BC in our study. Sensitivity in pcfDNA was determined using a validated MCED test classifier at 99% specificity. Results: Of 17 patients with suspicion of new NMIBC, 12 were diagnosed with BC after TURBT (Stage 0: N=6, I: N=5, II: N=1), and 10/12 were high grade (HG). Among patients with confirmed BC, ucfDNA sensitivity was 91.7% overall (11/12; 95% CI 61.5-99.8%) and 90% for HG (9/10). Whereas, pcfDNA sensitivity was 16.7% overall (2/12) and 10.0% for HG (1/10). Of 20 patients with suspicion of recurrent NMIBC, 14 were confirmed as BC (Stage 0: N=10, I: N=2, II: N=2) and 11/14 were HG. Sensitivity of ucfDNA for recurrence detection was 78.6% overall (11/14; 95% CI 49.2-95.3%), and 100% for HG (11/11), while pcfDNA sensitivity was 14.3% (2/14) overall and 18.2% (2/11) for HG. Notably, TAF in urine from NC patients (N=16) and patients with suspicion of new NMIBC found to be benign by TURBT (N=5) were all below the detection threshold. Among patients with suspicion of recurrent NMIBC but not found to have BC by TURBT, TAF estimates for 4/6 (66.7%) were above the detection threshold. Conclusions: We observed increased sensitivity in urine compared to matched plasma in patients with NMIBC, consistent with local shedding of bladder tumors into stored urine. A urine-based cfDNA assay with high sensitivity at high specificity, combined with non-invasive sampling, could be an ideal tool to use alongside the standard of care (e.g., cystoscopy) for clinical diagnosis and monitoring of BC. Further studies are needed to validate these findings and determine the clinical utility of ucfDNA in the diagnosis and surveillance of BC.

Acute Interstitial Nephritis in the Pediatric Population: A Review of Etiologic Associations, Histologic Findings, and Clinical Outcome

BACKGROUND

Acute interstitial nephritis (AIN) is an infrequent cause of acute kidney injury in the pediatric population with a broad range of etiologies. This retrospective review attempts to characterize AIN in the pediatric population, delineate etiologic factors, histologic features, and clinical outcome.

MATERIALS AND METHODS

Institutional pathology reports were queried for a diagnosis of AIN between 1/2010 and 10/2021. Archived slides and reports and clinical records were reviewed.

RESULTS

Twenty-four patients were identified whose ages ranged from 5 to 20 years. A 8 cases (37.5%) were characterized as tubulointerstitial nephritis and uveitis (TINU), 4 cases (16.7%) were associated with an autoimmune disease, 4 cases (16.7%) were likely drug induced, and 8 cases (37.5%) had unclear etiology.

DISCUSSION

Although all cases of drug induced interstitial nephritis contained eosinophils they were not exclusive to drug induced interstitial nephritis. A prominent plasma cell infiltrate was seen in both cases of Sjögren's associated interstitial nephritis. The vast majority (n = 18, 75%) showed an improved serum creatinine (<1 mg/dL) 1 year post diagnosis/at last follow-up. In this pediatric series of AIN, TINU contributed to a large subset of cases with known etiologies. On follow up, majority of the cases demonstrated recovery of renal function.

Focal Nodular Hyperplasia-Like Lesions With Glypican-3 Positivity in Infancy

PURPOSE AND CONTEXT

Glypican-3 is often used to discriminate between neoplastic and nonneoplastic liver. In focal lesions, positivity may be considered suggestive of a malignancy such as hepatoblastoma. However, glypican-3 is also normally expressed in the immature liver. We present a series of 5 cases of focal nodular hyperplasia (FNH)-like lesions arising in very young patients with glypican-3 expression and highlight the challenges these lesions present in the differential diagnosis of hepatoblastoma.

METHODS

Cases were obtained from the files of 3 tertiary pediatric hospitals. Clinical data were obtained from the electronic medical record and histopathologic material including immunohistochemical stains were reviewed.

KEY RESULTS

Patients were aged 2 weeks to 6 months with peak AFP levels ranging from 88.6 to 204,696 ng/mL. Microscopically, all were variably demarcated hepatocellular lesions with cords of hepatocytes, marked sinusoidal dilatation, and occasional fibrous bands and areas reminiscent of central scar with bile ducts. No significant cytologic atypia or increased mitotic activity were present. All showed glypican-3 expression and were negative for nuclear beta-catenin with intact reticulin framework.

CONCLUSIONS

Our study highlights the pitfalls of evaluating focal liver lesions in infants when high AFP levels and glypican-3 expression may reflect immaturity rather than neoplasia.

Evaluation of cell-free DNA approaches for multi-cancer early detection

In the Circulating Cell-free Genome Atlas (NCT02889978) substudy 1, we evaluate several approaches for a circulating cell-free DNA (cfDNA)-based multi-cancer early detection (MCED) test by defining clinical limit of detection (LOD) based on circulating tumor allele fraction (cTAF), enabling performance comparisons. Among 10 machine-learning classifiers trained on the same samples and independently validated, when evaluated at 98% specificity, those using whole-genome (WG) methylation, single nucleotide variants with paired white blood cell background removal, and combined scores from classifiers evaluated in this study show the highest cancer signal detection sensitivities. Compared with clinical stage and tumor type, cTAF is a more significant predictor of classifier performance and may more closely reflect tumor biology. Clinical LODs mirror relative sensitivities for all approaches. The WG methylation feature best predicts cancer signal origin. WG methylation is the most promising technology for MCED and informs development of a targeted methylation MCED test.

P11.45.B Improved overall survival following Stereotactic Radiosurgery for brain metastases - a single institution experience

Background

Brain metastases are increasingly common due to longer survival associated with advancements in treatment. Approximately 40% of cancer patients are diagnosed with brain metastases at some point during their disease. Stereotactic radiosurgery (SRS) avoids the neuro-cognitive toxicity associated with whole brain radiotherapy and has been increasingly offered as a treatment alternative for brain metastases. Combined with developments in systemic treatments, this approach has resulted in improved overall survival (OS). This study reviewed patients treated with single fraction SRS at our institution with a primary endpoint of overall survival.

Material and Methods

A retrospective review determined overall survival for 237 patients who received single fraction SRS for 451 brain metastases from solid tumours between 1st January 2017 and 31st December 2021. Primary tumour sites were classified as breast, kidney, colorectal, melanoma, lung or other. SPSS v.27 was used for Kaplan Meier OS determination. The median follow up was 10.3 months. Cox regression analysis assessed the association between Gross Tumour Volume (GTV) and OS.

Results

In this patient cohort, 60% (N=142) were female and 40% (N=95) were male, with a median age of 63 [32-85]. 63.7% (N = 151) had a solitary metastasis. Patients received a single fraction of 15, 17.5 or 20 Gy (prescribed to 80% isodose) dependent on the planning target volume (PTV) size and whether it was initial treatment or re-treatment. 71% of all patients were alive at 6 months with median OS of 12.0 months [10.6-13.4]. Primary tumour site significantly affected OS (Log rank, Chi squared 15.656, p0.008) with breast cancer patients (N=58) surviving longest with a median OS 16.0 months [13.6-18.4] followed by melanoma median OS 15.0 months [7.6-22.4], kidney cancer patients (N = 24) median OS 12.0 months [8.3-15.7] and lung patients (N=87) median OS 10.0 months [8.9-11.3]. The lowest median OS was for colorectal patients at 7.0 months [1.4-12.6]. However, considering the small sample size, N = 15, more data is needed to confirm the significance. The larger the GTV volume the lower the survival time (Chi squared 8.692, p 0.003).

Conclusion

71% of patients had an OS of 6.0 months or more with a median of 12.0 months. As expected, primary tumour site has a significant impact on OS, with breast cancer patients living longest. In addition, increasing GTV size is associated with significantly worse survival. Given the improved survival for these patients, the avoidance of neuro cognitive decline remains of paramount importance and outcomes for these patients need to be reported in future work.

Enterobius vermicularis-associated appendicitis: A 22-year case series and comprehensive review of the literature

INTRODUCTION

Enterobius vermicularis is known to be associated with appendicitis, however a causal relationship between Enterobius and appendicitis has not been established. The aim of this study was to explore the relationship between appendiceal Enterobius and histologic appendicitis.

METHODS

A retrospective review was performed of all pediatric appendectomies between 1997 and 2019. Patients with diagnosed with Enterobius were included for analysis. Patient demographics, operative findings, and pathologic reports were queried. Data were entered into an encrypted database and subsequently analyzed. A comprehensive review of the literature was also conducted.

RESULTS

Thirty-eight cases of Enterobius-associated appendicitis were identified out of 3541 (1.07%). Grossly normal appendices at operation were seen in 27% of patients. Inflammatory infiltrate was noted on histopathology in 78.3%, and Enterobius was considered to be the cause of that inflammation in 68.4%. The comprehensive literature review revealed 19 articles (1.87% incidence) that noted 35% of patients with appendiceal Enterobius had appendicitis on either histopathology or gross evaluation.

CONCLUSION

The high rate of inflammation on pathology found among our patients with pinworm appendicitis suggests an association with presentation as acute appendicitis. Our comprehensive review revealed a higher proportion of Enterobius appendicitis. Treatment with antihelminthic therapy is recommended.

LEVEL OF EVIDENCE (LOE)

Level IV(4)-case series and comprehensive review.

Placental Pathology and the Developing Brain

Abnormal neurodevelopmental outcomes are associated with multiple factors including prematurity, intrauterine infection, maternal comorbidities as well as fetal anomalies. Within the past decade, new standardized terminology in placental pathology has emerged, emphasizing the current understanding of processes that play a role in placental dysfunction. Factors playing a major role in the abnormal development of the placenta include abnormalities in blood flow and perfusion of the fetal and maternal compartments of the placenta termed fetal vascular malperfusion and maternal vascular malperfusion, respectively. Concepts reviewed include massive perivillous fibrin deposition, chronic villitis, meconium-associated injury as well as chorioamnionitis. Each have a temporal effect on the placental vascular tree and may reflect an altered maternal inflammatory response. In this article we highlight pathologic placental findings which when present can serve to explain, at least in part, altered neurodevelopment in the child, adolescent and adult. Lesions with a propensity for recurrence in future pregnancies are discussed.

A report on the review of archived osteosarcoma and EWING sarcoma specimens at the Biopathology Center, BONE Sarcoma Committee, Children’s Oncology Group

11524

Background: The Children’s Oncology Group (COG) Biorepository at the Biopathology Center (BPC), Nationwide Children’s Hospital, Columbus, OH contains archived tumor specimens submitted for COG study protocols. The BPC repository is utilized for numerous biology study aims with the goal of improved understanding of tumor pathophysiology, and impacts future clinical trials design and patient care. BPC pathologists perform quality assurance (QA) reviews of archival material before biospecimens are released for study. Since QA reviews are not routinely included in the submission process into the BPC, the quality and utility of tissue is often unclear. Therefore, a pathology quality assurance review was conducted to explore the utility of future testing on banked formalin fixed paraffin embedded (FFPE) Ewing Sarcoma and Osteosarcoma specimens. Methods: The BPC staff retrieved archival tumor cases for review between 06/2020 and 1/2022. One hematoxylin and eosin-stained slide per FFPE tissue block was digitally scanned for whole slide image (WSI) analysis and uploaded with a de-identified pathology report on a virtual slide-viewing platform. Five board certified pediatric pathologists with sarcoma expertise (AA, JB, SC, AS, JD) designed a digital QA review form and performed reviews. The QA review data collection form included diagnosis, volume of viable tumor, decalcification techniques, ancillary molecular/cytogenetic studies and a comment box to include additional noteworthy information. Results: During the study period, of the 1379 digitally prepared cases, 486 case reviews were completed, totaling 1192 digital slides reviewed. Of the reviewed cases, 465 (95%) were concordant with the diagnosis and had variable volumes of viable tumor (scant to adequate), while 33 (7%) of cases had no viable tumor (extensive necrosis or no tumor on the slide) and 21 (4%) had an alternative diagnosis (e.g. tumor submitted as osteosarcoma, re-classified as a chondromyxoid fibroma). Of the reviewed concordant cases, 271 (58%) were consistent with OS, 187 (40%) were consistent with ES and 7 (2%) were consistent non-ES round cell sarcomas (e.g. BCOR or CIC- rearranged sarcomas). Conclusions: Over ninety percent of reviewed specimens passed QA review, whereas the remaining failed due to diagnostic discordance or lack of viable tumor. Among cases with diagnostic concordance, variable volumes of tumor were present, including cases with scant viable tumors. Although QA reviews are time consuming, these results suggest QA reviews at tissue submission could potentially improve tissue quality available and timeliness of sample delivery for research. In addition, it would provide an opportunity for follow-up with sites to request submission of higher quality specimens and mitigate storage of tissue without potential for future use.

ARST2031: A study to compare early use of vinorelbine and maintenance therapy for patients with high risk rhabdomyosarcoma

TPS11591

Background: Patients with high-risk rhabdomyosarcoma (HR-RMS) continue to have poor outcomes with 3-year event free survival (EFS) rates of 30% or less despite chemotherapy dose intensification on recent cooperative group RMS trials. Vinorelbine (VINO) has demonstrated clinical activity in RMS patients with relapsed/refractory disease and shown to provide a survival benefit when given with oral cyclophosphamide as maintenance chemotherapy for a select group of patients that achieved first complete remission. Methods: ARST2031 is a randomized Phase 3 trial with the primary aim to compare event-free survival (EFS) of patients with HR-RMS treated with vincristine, dactinomycin and cyclophosphamide (VAC) followed by maintenance with vinorelbine and oral cyclophosphamide (VINO-CPO) or vinorelbine, dactinomycin and cyclophosphamide (VINO-AC) followed by maintenance with VINO-CPO. Patients are stratified by histology and randomly assigned to VAC followed by VINO-CPO maintenance or VINO-AC followed by VINO-CPO maintenance. To be eligible, patients must be ≤ 50 years of age at the time of enrollment with newly diagnosed RMS except adult-type pleomorphic, based upon institutional histopathologic classification. All patients must have Stage 4 disease and patients diagnosed with embryonal RMS (ERMS) must be ≥ 10 years of age. Patients with malignant cytology in cerebrospinal fluid, intra-parenchymal brain metastases, or diffuse leptomeningeal disease are excluded. The study was activated on September 13, 2021 and is anticipated to enroll approximately 4 patients per month. The planned sample size is 100 patients, with approximately 50 patients randomized to each arm. Safety and feasibility of VINO-AC will be assessed in the first 8 patients prior to randomization. The study will have power of 0.8 to detect a hazard ratio of 0.61 (74 events in total) when the one-sided Type I error rate is 0.10, with 30 months of accrual and 2 years of follow-up. The hazard ratio of 0.61 was determined by assuming piecewise exponential distributions and specifying the 2-year EFS of 46% vs. 28% and long-term EFS of 32% vs. 16%, based on prior outcome data. Biospecimens will be collected and banked for future use. Clinical trial information: NCT04994132.

Pediatric Hypersensitivity Pneumonitis: Clinicopathologic Characteristics of Two Cases with Fungal Triggers

Background Hypersensitivity pneumonitis (HP) infrequently presents in childhood. Asthma or a pneumonia-like clinical presentation may lead to diagnostic delay, especially in children. Case Report: We present two cases of HP, a 6-year-old (Case 1) male and a 5-year-old (Case 2) female. Both cases had a negative infectious work-up and patchy ground glass lung opacities on chest computed tomography. Lung biopsies demonstrated lymphocytic bronchiolitis with granulomatous interstitial and peribronchial inflammation. Serology demonstrated elevated immunoglobulin precipitins toward Thermoactinomyces and Aspergillus species in Case 1 and Aspergillus fumigatus in Case 2. Both patients received steroid therapy and had symptom resolution. Conclusions: A diagnosis of HP should be considered in pediatric lung biopsies with granulomatous interstitial and peribronchial inflammation, if infectious etiologies are excluded. Integration of clinical, radiological, and laboratory findings can facilitate a timely diagnosis.

Solid pancreatic masses in children: A review of current evidence and clinical challenges

Pancreatic tumors in children are infrequently encountered in clinical practice. Their non-specific clinical presentation and overlapping imaging characteristics often make an accurate preoperative diagnosis difficult. Tumors are categorized as epithelial or non-epithelial, with epithelial tumors further classified as tumors of the exocrine or endocrine pancreas. Although both are tumors of the exocrine pancreas, solid pseudopapillary neoplasm is the most prevalent solid pancreatic tumor in children, while pancreatoblastoma is the most common malignant tumor. Insulinoma is the most common pediatric pancreatic tumor of the endocrine pancreas. Malignant tumors require a complete, often radical, surgical resection. However, pancreatic parenchyma-sparing surgical procedures are utilized for benign tumors and low-grade malignancy to preserve gland function. This review will discuss the epidemiology, pathophysiology, clinical and diagnostic characteristics, and management options associated with both common and rare solid pancreatic masses in children. We will also discuss current challenges encountered in their evaluation and treatment.

Concurrent bronchopulmonary foregut malformations: a rare case of right-sided extralobar pulmonary sequestration and bronchogenic cyst

Background

Bronchopulmonary foregut malformations are rare congenital malformations. It is extremely rare to have malformations that occur simultaneously. There is literature to show that extralobar sequestration is associated with other congenital anomalies, most commonly diaphragmatic hernias, and also with other bronchopulmonary foregut malformations (e.g., extralobar sequestration and congenital pulmonary airway malformations). However, very few case reports were found that reported extralobar sequestration and foregut duplication cysts and only one report of a right-sided complex foregut malformation with pulmonary sequestration.

Case presentation

We present a case of a 3-month-old male infant with a prenatal diagnosis of a cystic lung lesion who, after developing symptoms of respiratory distress, was found to have concurrent right-sided extralobar pulmonary sequestration and a mediastinal bronchogenic cyst.

Conclusions

The concurrent occurrence of these malformations in one patient could help support the theory that these malformations result from an early error in development during the time when both the lung buds and foregut are developing simultaneously.

Peripheral ameloblastic fibro-odontoma-Report of 2 cases of a very rare entity

Ameloblastic fibro-odontoma (AFO) is a rare benign mixed odontogenic tumor that affects children and young adults. AFO occurs mainly intraosseous. Extraosseous AFO is extremely rare. We report 2 cases of rare peripheral ameloblastic fibro-odontoma in 2- and 12-year-old female patients. Microscopic examination revealed a benign proliferation of odontogenic epithelium associated with a dentinoid material distributed within a cell-rich mesenchymal stroma resembling dental papilla. Simple surgical excision of the lesion is usually curative. There was no recurrence after a short period of follow-up. Clinicians should be cognizant of this rare entity, which can be considered in a differential diagnosis of gingival growths that are noted in early childhood.

Wrong Tissue in Block

OBJECTIVES

Maintaining specimen identity during surgical pathology tissue processing is critical. Epic Beaker Laboratory Information System requires sequential scanning of specimen label and grossed blocks (block confirmation) to ensure specimen identity. We report our institution's experience with wrong tissue in block (WTIB) grossing errors before and after adopting block confirmation.

METHODS

During the first 18 months of Beaker implementation, block confirmation was not required. We then mandated block confirmation for a 3-month period. To ensure compliance, we then built a "hard stop" feature that prevents scanning any unconfirmed blocks onto a packing list. We reviewed WTIB incidents pre- and postimplementation of these solutions.

RESULTS

Before using block confirmation, we had WTIB incidents involving 17 (0.043%) of 38,848 cases. When we mandated block confirmation use, we had WTIB involving 2 (0.043%) of 4,646 cases. After implementing the hard stop feature, we had WTIB incidents involving 2 (0.005%) of 42,411 cases. Overall, there was an 88.4% (0.043% vs 0.005%; P < .001) reduction in WTIB incidents using block confirmation with a hard stop.

CONCLUSIONS

Beaker is a customizable platform that can be tailored to a laboratory's workflow. By using barcoding, implementing custom-built features, and improving workflow protocols, we significantly reduced WTIB errors.

Prospective Comparative Evaluation of Post-extraction Bleeding in Cardiovascular-Compromised Patients with and without Antiplatelet Medications

BACKGROUND AND OBJECTIVE

A considerable number of patients consulting a dental surgeon are on antiplatelet therapy, and an interruption of these agents for 3 to 7 days has been practised by majority of them prior to dental surgical intervention fearing excessive bleeding, risking the patient for the occurrence of adverse thrombotic events. The dental and medical literature shows a very low risk of excessive bleeding associated on the continuation of antiplatelet therapy. The objective of this study is to compare the bleeding following single-firm molar tooth extraction in patients who interrupt and those who continue antiplatelet therapy perioperatively.

METHODOLOGY

This is a prospective descriptive study on 170 patients on long-term low-dose antiplatelet therapy with 2 groups, each containing 85 patients-Group 1 with patients who interrupted antiplatelet therapy for 5 days before extraction and Group 2, patients who continued it perioperatively. A single molar tooth extraction was done under local anaesthesia with a vasoconstrictor. Gauze pressure pack was placed for 60 min. Socket was observed every 15 min for 1 h to look for excessive post-extraction bleeding.

RESULTS

No statistically significant differences were found in post-extraction bleeding between the patients who stopped antiplatelet therapy and those who continued it.

CONCLUSION

The bleeding risk when continuing long-term low-dose antiplatelet therapy following a single molar tooth extraction is minimal. Bleeding, if excessive, can be easily controlled by gauze pressure pack or other local haemostatic agents. Thus, dental extractions can be performed on these patients without interrupting the antiplatelet drug pre-operatively provided a thorough medical history, physician's consent and coagulation profile have been obtained prior to the procedure.

A Post-Auricular Accessory Tragus

Here, we document a rare and unique presentation of an accessory tragus (AT). A 3-year-old male presented with a 2-cm congenital post-auricular mass on his right side. Upon resection and histologic examination, the mass demonstrated histologic features consistent with an AT. To the best of our knowledge, this is the first reported case of an AT presenting posterior to the auricle.

Generalized infantile myofibromatosis with visceral involvement presenting as diffuse hypopigmented macules at birth

The initial clinical presentation of infantile myofibromatosis can vary from subtle skin changes to large tumors. Here, we describe a case of congenital generalized infantile myofibromatosis which presented with diffuse hypopigmented macules, some with subtle atrophy and telangiectasia. Further workup revealed visceral involvement which led to treatment with systemic chemotherapy. Awareness of this rare clinical presentation is crucial to expedite workup and treatment given the poor prognosis in infants with visceral involvement.

The prognostic significance of anaplasia in childhood rhabdomyosarcoma: A report from the Children's Oncology Group

BACKGROUND

Established prognostic indicators in rhabdomyosarcoma (RMS), the most common childhood soft tissue sarcoma, include several clinicopathologic features. Among pathologic features, anaplasia has been suggested as a potential prognostic indicator, but the clinical significance of anaplasia remains unclear.

METHODS

Patients enrolled on one of five recent Children's Oncology Group clinical trials for RMS (D9602, n = 357; D9802, n = 80; D9803, n = 462; ARST0331, n = 335; and ARST0531, n = 414) with prospective central pathology review were included in this study. Clinicopathologic variables including demographic information, risk group, histologic subtype, and anaplasia were recorded along with overall survival (OS) and failure-free survival (FFS) with failure defined by recurrence, progression, or death. The log-rank test was used to compare OS and FFS.

RESULTS

Anaplasia was more common in embryonal RMS (27% of all embryonal RMS) than other subtypes of RMS (11% for alveolar RMS, 7% for botryoid RMS, 11% for spindle cell RMS). On multivariate analyses, anaplasia was not an independent prognostic factor in RMS (OS:hazard ratio (HR) = 1.12, p = 0.43; FFS:HR = 1.07, p = 0.56) across all subtypes or within embryonal RMS only (OS:HR = 1.41, p = 0.078; FFS:HR = 1.25, p = 0.16). Among tumors with TP53 mutations, 69% had anaplasia, while only 24% of tumors with anaplasia had a tumoral TP53 mutation.

CONCLUSIONS

Anaplasia is not an independent indicator of adverse outcomes in RMS. Emerging information on the prognostic significance of TP53 mutations raises the possibility that anaplasia may be a surrogate marker of TP53 mutations in some cases. Tumoral TP53 mutation status may be investigated as a prognostic indicator in future studies.

Robot-Assisted Laparoscopic Resection of the Mesonephric Duct Remnant in a Patient with Zinner Syndrome

Introduction: A 17-year-old male with Zinner syndrome, a right seminal vesicle cyst, and a solitary left kidney presented with chronic pelvic pain. Previous surgeons had attempted robot-assisted laparoscopic seminal vesicle cyst aspiration and transurethral resection of the ejaculatory duct. Neither surgery provided sustained symptom relief. Abdominal and pelvic MRI showed a cystic structure lodged between the prostate and bladder. The right seminal vesicle, kidney, and ureter were not observed. Materials and Methods: A robot-assisted laparoscopic seminal vesiculectomy was planned. Dissection distal to the right vas deferens and between the bladder neck and prostate revealed a cystic seminal vesicle-like structure. Attached to this was a tubular structure coursing deep to the vas deferens from the right renal fossa. This was presumed to be a dysplastic ureter. The dysplastic ureter was transected from the seminal vesicle and the seminal vesicle was marsupialized to the deep pelvis. Proximally, the dysplastic ureter was transected and left open. Results: Histologic assessment of the specimen revealed an ∼12.1 cm tubular mesonephric remnant. The postoperative course was uncomplicated. At 6 months follow-up, the patient remains free of symptoms with preserved ejaculatory volume. Conclusions: Mesonephric duct abnormalities and symptoms present on a spectrum. We present a safe and effective resection of a mesonephric duct remnant from a 17-year-old male with Zinner syndrome. A robotic approach localized to the right allowed for excellent observation without compromising left-sided genitourinary anatomy. In males presenting with renal agenesis and pelvic symptoms, clinicians should be suspicious of Zinner syndrome and other mesonephric abnormalities.

Robust, 3-Dimensional Visualization of Human Colon Enteric Nervous System Without Tissue Sectioning

BACKGROUND & AIMS

Small, 2-dimensional sections routinely used for human pathology analysis provide limited information about bowel innervation. We developed a technique to image human enteric nervous system (ENS) and other intramural cells in 3 dimensions.

METHODS

Using mouse and human colon tissues, we developed a method that combines tissue clearing, immunohistochemistry, confocal microscopy, and quantitative analysis of full-thickness bowel without sectioning to quantify ENS and other intramural cells in 3 dimensions.

RESULTS

We provided 280 adult human colon confocal Z-stacks from persons without known bowel motility disorders. Most of our images were of myenteric ganglia, captured using a 20× objective lens. Full-thickness colon images, viewed with a 10× objective lens, were as large as 4 × 5 mm². Colon from 2 pediatric patients with Hirschsprung disease was used to show distal colon without enteric ganglia, as well as a transition zone and proximal pull-through resection margin where ENS was present. After testing a panel of antibodies with our method, we identified 16 antibodies that bind to molecules in neurons, glia, interstitial cells of Cajal, and muscularis macrophages. Quantitative analyses demonstrated myenteric plexus in 24.5% ± 2.4% of flattened colon Z-stack area. Myenteric ganglia occupied 34% ± 4% of myenteric plexus. Single myenteric ganglion volume averaged 3,527,678 ± 573,832 mm³ with 38,706 ± 5763 neuron/mm³ and 129,321 ± 25,356 glia/mm³. Images of large areas provided insight into why published values of ENS density vary up to 150-fold-ENS density varies greatly, across millimeters, so analyses of small numbers of thin sections from the same bowel region can produce varying results. Neuron subtype analysis revealed that approximately 56% of myenteric neurons stained with neuronal nitric oxide synthase antibody and approximately 33% of neurons produce and store acetylcholine. Transition zone regions from colon tissues of patients with Hirschsprung disease had ganglia in multiple layers and thick nerve fiber bundles without neurons. Submucosal neuron distribution varied among imaged colon regions.

CONCLUSIONS

We developed a 3-dimensional imaging method for colon that provides more information about ENS structure than tissue sectioning. This approach could improve diagnosis for human bowel motility disorders and may be useful for other bowel diseases as well.

Liver Pathology in Mitochondrial Complex I Deficiency from Bi-Allelic Mutations in NDUFS2: A Report of Findings at Autopsy

Background: Mitochondriopathies are a heterogeneous group of genetic disorders with a wide array of symptomatology, organ system involvement, and inheritance patterns. Neonatal presentation can be fatal with neuromuscular dysfunction, lactic acidosis and hepatic failure. Historic literature has numerous phenotypic illustrations; however, genotypic correlation is limited. With improved testing methods, genotype-phenotype correlation is now increasingly feasible as demonstrated herein. Case Report: We present liver pathology findings in an infant who expired with a diagnostic suspicion of a mitochondrial disorder. Postmortem hepatocyte hypereosinophilia with microvesicular steatosis associated with ultrastructural findings of mitochondrial hyperplasia supported a mitochondriopathy. Genetic testing eventually confirmed mitochondrial complex I deficiency from bi-allelic mutations in NDUFS2. Conclusions: Morphologic attributes can assist in diagnosis of mitochondriopathies before specific genetic testing results are available. This case also highlights that diagnostic information can be gained from ultrastructural examination of postmortem liver tissue.

Evaluation of Changes in the Alar Base Width Following Lefort 1 and AMO with Conventional Alar Cinch Suturing: A Photographic Study of 100 Cases

Objective

To assess the changes in alar base width in patients who underwent Lefort 1 osteotomy with anterior maxillary osteotomy (AMO), where conventional alar cinch suturing was done to control the alar base widening.

Materials and Methods

This study was conducted on pre-operative and post-operative photographs of 100 female patients aged between 18 and 30 years who underwent Lefort 1 osteotomy with AMO. The derived values were then compared and analysed using t test.

Results

The mean alar base width pre-operatively was 14.11 mm and post-operatively was 15.28 mm. The mean increase in alar base width was 1.176 mm. The result indicated a definitive change between pre-operative and post-operative alar base widths with mean increase in width of 1.176 mm (P = 0.000), which is clinically not very significant.

Conclusion

The effect of Lefort 1 osteotomy on the alar base can be well controlled by the conventional alar cinch suturing without any additional anchorage on the ANS with predictable results.

Sub-acute neonatal hemochromatosis in an infant with hypoplastic left heart syndrome on ventricular assist device awaiting transplantation

Single-ventricle pediatric patients, amongst other children waiting for OHT, are a vulnerable population, especially if candidacy is established before any palliation. NH is a rare disease with poor prognosis in the post-natal period. We present a case of sub-acute NH diagnosed in an infant with HLHS who was listed for OHT while bridged with a pulsatile paracorporeal VAD, with an emphasis on the evolution of the condition throughout the patient's clinical course and the ultimate decision for compassionate deactivation of VAD.

Sclerosing Epithelioid Fibrosarcoma of the Bone With Rare EWSR1-CREB3L3 Translocation Driving Upregulation of the PI3K/mTOR Signaling Pathway

Sclerosing epithelioid fibrosarcoma (SEF) is an uncommon neoplasm that rarely presents in bone. It is characterized by epithelioid cells arranged in nests and single-file cords within a sclerotic stromal background which may mimic neoplastic bone. SEF harbors an EWSR1 translocation, which may complicate its distinction from Ewing sarcoma in cases with histomorphologic overlap. We present a diagnostically challenging case of SEF in the mandible of a 16-year-old girl. Our experience highlights the lack of specificity of traditional morphology and EWSR1 break-apart fluorescent in situ hybridization. Open-ended RNA-based fusion gene testing coupled with MUC4 immunohistochemistry aided the eventual diagnosis in this case. Herein, we report the third case of SEF with EWSR1-CREB3L3 translocation and show that this fusion leads to aberrant upregulation of the phosphoinositide 3-kinase/mammalian target of rapamycin signaling pathway in heterologous cell models.

Distal rectal skip segment Hirschsprung disease: Case report and review of literature

Background: Lack of ganglion cells on adequate suction rectal biopsy is the gold standard for diagnosis of neonatal Hirschsprung disease (HD), and the presence of ganglion cells precludes such a diagnosis. Case report: A 10-day old male neonate presented with clinical symptoms concerning for HD. However, suction rectal biopsies demonstrated submucosal ganglion cells on the distal suction rectal biopsies (2 cm from anal verge) and not on the proximal (3 cm from anal verge), with similar findings on repeat biopsies. Clinical suspicion remained high, and diagnostic laparoscopy with intraoperative biopsies confirmed aganglionosis with a sigmoid transition. A pull through resection confirmed the diagnosis of distal rectal skip segment HD (SSHD) with a ∼6 cm length of circumferential aganglionosis extending into the proximal sigmoid. Conclusions: Discordant results on suction rectal biopsies should raise the possibility of SSHD. Awareness of the entity can facilitate timely definitive management in neonatal period.

Abstract 3372: Cell-free DNA (cfDNA) fragment length patterns of tumor- and blood-derived variants in participants with and without cancer

Previous studies on transplanted tissue or single cancers indicated that cfDNA variant fragment lengths reflect their respective source. The Circulating Cell-free Genome Atlas (NCT02889978) study provides an opportunity to examine cfDNA variant fragment lengths across tumor types and describe the nature of cfDNA variants derived from different sources.

Blood samples (N=1406) were evaluated from participants with (n=845) and without (n=561) cancer; cancer samples included 339 breast, 118 lung, 69 prostate, 45 colorectal, 27 uterine, 26 pancreas, 26 renal, 24 esophageal, 22 lymphoma, 19 head/neck, and 17 ovarian (113 remaining samples represented cancers with ≤15 samples each). cfDNA and genomic DNA from white blood cells (WBC) were subjected to a high-intensity targeted panel (507 genes, 60000X) with error-corrected sequencing; 533 samples also had matched tumor biopsy tissue subjected to whole-genome sequencing (30X).

Somatic single-nucleotide variants (SNVs; that passed noise filters) were identified and classified using the sequencing results into one of four categories: tumor biopsy-matched (TBM; present in cfDNA and biopsy), WBC-matched (WM; present in cfDNA and WBC), non-matched (NM; low probability [P&lt;0.01] of being WBC-derived), or ambiguous (AMB; unidentifiable source). Fragment lengths of reference and SNV alleles were recorded. A statistical model based on fragment lengths was built to predict the likelihood that an SNV belonged to a WBC-like source without using the WBC sequencing results.

A total of 21604 SNVs were identified. The proportion of SNVs from each category were: 4% TBM, 68% WM, 19% NM, and 8% AMB. The number of samples (non-mutually exclusive) that had each SNV category were 152 TBM, 1338 WM, 499 NM, and 761 AMB.

Across categories, the median (SD) length of fragments containing the reference allele was 167 (16.3). Median (SD) fragment lengths of TBM, WM, NM, and AMB were 156 (22.2), 169 (14.8), 158 (20.8), and 165 (17.8), respectively. AMB and WM median SNV fragment lengths were similar to that of the reference allele, suggesting that fragment length shifts are minimal in SNVs derived from clonal hematopoiesis (CH). Fragment lengths of TBM and NM SNVs were similar; further, most NM SNVs came from cfDNA samples in the cancer cohort, suggesting that NM SNVs may be tumor-derived. As expected in a population with a median (SD) age of 61 (12.2), most SNVs occurred in the WM category.

The prediction model distinguished TBM from WM SNVs with an AUC of 0.87. However, at a specificity of 98% (to match filtering based on WBC sequencing), false-negative rates were 35% (TBM) and 52% (NM).

Together, these data suggest that source prediction based on fragment length alone is less robust than source assignment using individual-matched WBC sequencing, highlighting the importance of accounting for CH-derived SNVs when using targeted cfDNA-based approaches for cancer detection.

Citation Format: Earl Hubbell, Tara Maddala, Oliver Venn, Eric Scott, Susan Tang, Archana Shenoy, Alex Aravanis. Cell-free DNA (cfDNA) fragment length patterns of tumor- and blood-derived variants in participants with and without cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3372.

Gastric Plexiform Fibromyxoma: A Great Mimic of Gastrointestinal Stromal Tumor (GIST) and Diagnostic Pitfalls

Through a multicenter study, we collected seven cases of gastric plexiform fibromyxoma including four females and three males, 21 to 79 y old (46.1 ± 10.1). All cases showed a unilocular lesion measuring 0.3 to 17 cm (5.3 ± 2.4), arising from antrum (5/7) or body (2/7). Six of the seven cases had intraoperative frozen sections and/or endoscopic ultrasound fine needle aspiration (EUS-FNA), and all of them were preoperatively or intraoperatively diagnosed as gastrointestinal stromal tumor (GIST). EUS-FNA material showed markedly elongated spindle cells with streaming oval to elongated nuclei with rounded ends. Histologically, the tumors exhibited a plexiform growth pattern and were composed of a rich myxoid stroma and cytologically bland uniform spindle cells without mitotic figures, with the exception of one case which displayed nuclear pleomorphism and increased mitosis. Immunostains showed the tumor cells to be focally positive for SMA (6/6), focally and weakly positive for desmin (3/6) and caldesmon (2/3), negative for CD117 (0/7), CD34 (0/7), DOG1 (0/4), and S100 (0/5). No mutations were identified on Next-Generation Sequencing test, and no loss of SDHB immunoreactivity was identified in the tumor with nuclear pleomorphism. One case was treated with Gleevec because of the initial diagnosis of GIST. All patients had a follow-up for up to 11 y, with no tumor recurrence or metastasis reported. Our results suggest that gastric plexiform fibromyxoma is rare and may be underrecognized and misinterpreted as GIST during intraoperative frozen section or preoperative EUS-FNA diagnosis without immunostains leading to inappropriate treatment.

Utility of Esophagogastroduodenoscopy in the Evaluation of Uncomplicated Abdominal Pain in Children

Esophagogastroduodenoscopy (EGD) is commonly performed for abdominal pain in children, and in the presence of alarm symptoms, the diagnostic yield of this procedure is high. The aim of this study was to investigate the utility of EGD when performed for uncomplicated abdominal pain in children in the absence of alarm symptoms. Charts of all children less than 18 years of age who underwent EGD at the University of Florida between January 2016 and October 2018 were reviewed. Of 1478 children who underwent EGD for any indication, 287 patients (male-to-female = 123:164) were discovered to have undergone EGD, in the absence of colonoscopy, for uncomplicated acute or chronic abdominal pain, nausea, vomiting, gastroesophageal reflux, and/or dyspepsia, with no alarm symptoms. A significant change in clinical management was noted in 20 (7.0%) children. The findings of this procedure changed clinical management in a minority of our study participants.

Utility of Various Bronchoscopic Modalities in Lung Cancer Diagnosis

Background: Bronchoscopy and different techniques to obtain tissue sample form the cornerstone of lung cancer diagnostics. The utility, specificity and sensitivity of various techniques are compared against each other and also in relation to the tumour type, location and morphology. Aim: To assess and compare the utility of various bronchoscopic procedures in lung malignancies. Study also compares the utility of these techniques on tumour site, morphology and cell type. Methods: One hundred and fifty six patients with suspected malignancies in whom bronchoscopy was deemed as the primary diagnostic procedure were selected. These patients underwent bronchoscopic lavage, brushings and biopsy. Samples were assessed by microbiological, cytology and histopathological analysis. Results: Bronchoscopic procedures have a high diagnostic accuracy of 81.25% in confirming lung malignancies in central tumours and also in non-accessible peripheral tumours. Bronchial brushings had the highest yield in central tumours (55.9%) and a reasonably good yield even in perpipheral tumours (40.8%). When all the modalities were compared against each other, brushings was the single most decisive technique as it alone yielded a diagnosis in a significant 33% of cases, whereas the comparative diagnosis by biopsy alone was in a minority 7.6% of cases.