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Background: The increased accessibility and utilization of molecular testing including next-generation sequencing (NGS) has impacted the practice of pediatric pathology, with diagnostic, prognostic, and therapeutic implications for our patients. This survey is the first to describe the utilization of molecular testing in the routine practice of pediatric pathology for the care of children with known or suspected solid tumors., Procedure: The Society for Pediatric Pathology Practice Committee distributed a survey to our membership asking 25 questions about training, practice setting, molecular ordering practices, and barriers to testing., Results: Seventy-five pathologists responded to the survey. The survey provides valuable insight into the current use of molecular testing for the care of children with known or suspected solid tumors. Most respondents reported that they are increasingly using a variety of molecular techniques, with increased use over time, and that NGS is useful., Conclusions: These results highlight a variety of barriers to molecular testing, including cost, insurance coverage, turnaround time, limitations of available assays (including limited coverage of pediatric-specific alterations), and difficulty in determining the most appropriate test to order. These data may be useful in supporting pediatric pathologists in their practice., (© 2024 Wiley Periodicals LLC.)

Context: Next-generation sequencing-based approaches using RNA have increasingly been used by clinical laboratories for the detection of fusion genes, intragenic rearrangements, and exon-skipping events. Correspondingly, the College of American Pathologists (CAP) has advanced RNA sequencing proficiency testing (PT) to ensure optimal performance of these assays., Objective: To report on laboratory performance and practices of RNA sequencing for the detection of fusion genes, intragenic rearrangements, and exon-skipping events using CAP PT data from 8 mailings (2018-A through 2021-B)., Design: CAP PT RNA sequencing program results from 153 laboratories across 24 proficiency test specimens, interrogating 22 distinct engineered fusion transcripts, were analyzed for correct identification of the fusion event, associated performance variables, and laboratory practices., Results: Overall, the 4-year program detection rate (sensitivity) was 95.5% (1486 of 1556 results). False-negative rates were 3.6% (53 of 1463) and 18.3% (17 of 93) for fusion gene and intragenic rearrangement/exon-skipping events, respectively. Only 19 false-positive results were reported among the 8 PT mailings, and most were likely the result of preanalytical or postanalytical errors. There were no practice characteristics (eg, instrumentation, sequencing method) significantly associated with the fusion detection results., Conclusions: These data reveal a high overall sensitivity and specificity for fusion gene detection by participating laboratories using clinical RNA sequencing. Performance was comparable across all laboratories, regardless of methodology. The fraction of false-negative results for intragenic rearrangement/exon-skipping events was greater than that for the chimeric fusion genes. False-negative results could not be attributed to any specific practice characteristics., Competing Interests: The identification of specific products or scientific instrumentation is considered an integral part of the scientific endeavor and does not constitute endorsement or implied endorsement on the part of the author, Department of Defense (DoD), or any component agency. The views expressed in this article are those of the authors and do not reflect the official policy of the Department of Army/Navy/Air Force, DoD, or US government., (© 2024 College of American Pathologists.)

Background/objectives: Rhabdomyosarcoma (RMS) is characterized by the expression of the myogenic regulatory protein MYOD1. Histologic types include alveolar, embryonal (ERMS), and spindle cell sclerosing RMS (SRMS). SRMS harbors MYOD1 mutations in a subset of adult cases in association with poor prognosis., Design/methods: To study the level of MYOD1 protein expression and its clinical significance, we have analyzed variable numbers of pediatric (<18 years of age) and adult (age range ≥18 to 35 years) ERMS and SRMS cases for presence or absence of MYOD1 immunoreactivity in correlation with clinical outcome and MYOD1 L122R mutations., Results: Lack of MYOD1 immunoreactivity, identified in 23.8% of nonalveolar RMS (non-ARMS) cases, was more prevalent in SRMS (44%) than ERMS (17.2%) and was significantly associated with low overall survival and unfavorable tumor sites (p < .05). Lack of MYOD1 immunoreactivity was not associated with MYOD1 L122R mutations, which were identified in 3/37 (8%) cases including only two of 31 (6.5%) pediatric cases, one of 11 or 9% pediatric SRMS, and one case of infant ERMS., Conclusion: These studies highlight the prognostic role of MYOD1 in non-ARMS. Lack of MYOD1 immunoreactivity is associated with poor prognosis in ERMS and SRMS. MYOD1 gene mutations are generally infrequent in pediatric RMS. Although mutations are predominant in SRMS, they may exceptionally occur in infantile ERMS., (© 2021 Wiley Periodicals LLC.)

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.

Functional performance evaluations and intervention planning for children and youth is informed by comparisons of their performance to normative standards. The literature contains little data regarding the developmental norms for children on pinch strength. A random sample of 414 children was assessed on three separate measures of pinch strength. Pad-to-pad, three-jaw chuck, and lateral pinch were evaluated using the B & L Engineering pinch gauge while utilizing the standard positioning recommended by the American Society of Hand Therapists. The results were divided into distinct categories for 5-to 12-year-olds. The resulting normative data provide standards for pinch strength in children to be used in the clinical setting.