About

Dr. Casey J. Mehrhoff received her Master of Science in Biomedical Sciences and her medical degree from Kansas City University of Medicine. She completed her Pediatric Residency at Loyola University Medical Center in Chicago and her Pediatric Hematology/Oncology Fellowship at Ann & Robert H. Lurie Children's Hospital of Chicago. She is currently an Assistant Professor of Pediatrics at the University of Utah within the Division of Pediatric Hematology/Oncology at Primary Children's Hospital. Her clinical focus is on pediatric patients with solid tumor malignancies, with a specific emphasis on patients diagnosed with rare tumors and those with cancer predisposition syndromes. She is the co-director and co-founder of the Pediatric Multidisciplinary Thyroid Team and the Pediatric Multidisciplinary Melanoma program, and she is involved with these specialties on a national level. Additionally, she provides care and cancer screening for patients with cancer predisposition syndromes such as Li Fraumeni Syndrome, DICER1, and Familial Adenomatous Polyposis at the high-risk genetics cancer predisposition clinic at Huntsman Cancer Institute. Her research interests include translational research and clinical trials.

Research topics

• Oncology
• Internal medicine
• Medicine
• Dermatology
• Biology
• Pathology
• Pharmacology
• Cancer research
• Chemistry

Selected publications

• A Case of Pediatric Spitz Melanoma With a <i> <scp>ZEB2</scp> :: <scp>ALK</scp> </i> Fusion

  Pediatric Dermatology · 2026-04-08

  articleOpen accessSenior authorCorresponding

  We present a rare case of Spitz melanoma in a 3-year-old male patient with a ZEB2::ALK fusion. This ALK-fused tumor exhibited aggressive behavior, recurring after an initial wide local excision and progressing despite neoadjuvant immunotherapy with a PD-1 inhibitor. Following a second surgical resection and adjuvant radiation therapy, the patient was started on adjuvant targeted therapy with lorlatinib, an ALK kinase inhibitor. This report illustrates the role of immunotherapy and targeted therapy in melanoma treatment.

  PublisherDOI

• Ex vivo oocyte retrieval for fertility preservation in an adolescent patient with recurrent ovarian dysgerminoma: a case report and review of the literature

  F&S Reports · 2025-01-29 · 2 citations

  articleOpen access

  Objective: To describe fertility preservation via ex vivo oocyte retrieval for an adolescent patient undergoing oophorectomy for recurrent ovarian dysgerminoma and to review the available literature regarding this technique. Design: Case report and literature review. Subjects: A 17-year-old female with a medical history of right ovarian dysgerminoma treated with oophorectomy 3 years prior, who presented with a retroperitoneal mass noted during surveillance. Biopsy of the mass and remaining ovary confirmed recurrent stage III ovarian dysgerminoma. The patient desired fertility preservation. Ovarian tissue cryopreservation and traditional transvaginal oocyte retrieval were contraindicated because of the ovarian malignancy. Exposure: The patient underwent controlled ovarian hyperstimulation with gonadotropins followed by laparotomy and left salpingo-oophorectomy 36 hours after ovulation trigger. An ex vivo retrieval of oocytes was performed under both direct visualization and ultrasound guidance in the operating room after excision of the ovary and isolated using a "mobile IVF" setup. Main Outcome Measures: Number of meiosis II oocytes cryopreserved. Results: A total of 12 meiosis II oocytes were retrieved from the ovary and were successfully cryopreserved. The patient tolerated the procedure well and has since completed chemotherapy. Conclusion: The combination of controlled ovarian hyperstimulation followed by ex vivo oocyte retrieval provides select patients with an opportunity for fertility preservation that may have otherwise faced a complete loss of fertility. In this case, the patient was able to preserve oocytes without jeopardizing her health status or delaying cancer therapy.

  PublisherOA PDFDOI

• Primary intracranial malignant melanoma in a pediatric patient: A rare case report

  JAAD Case Reports · 2025-07-25

  articleOpen accessSenior author
  PublisherDOI

• Navigating Multidisciplinary Care in Pediatric Thyroid Carcinoma: Insights From Children's Oncology Group Sites

  Pediatric Blood & Cancer · 2025-07-18

  letterOpen access1st authorCorresponding

  To the Editor, Pediatric thyroid carcinoma is rare, with an incidence of 1.2 per 100,000 individuals under 20 years of age, increasing to 3.5 per 100,000 among adolescents aged 15–19 years [1]. Although the overall prognosis is excellent, pediatric patients with thyroid carcinoma may not achieve a complete response with the current management approach. Furthermore, the unique molecular and clinical characteristics of pediatric thyroid carcinoma can influence its clinical behavior and prognosis [2]. Papillary thyroid carcinoma (PTC) constitutes 80%–90% of pediatric cases, with cervical lymph node metastasis present in 30%–40% and lung metastasis in approximately 20%. While patients experience a survival rate > 95%, less than 20% of patients with lung metastasis achieve a complete response to therapy and have recurrence rates of 20%–30% [1-5]. Follicular thyroid carcinoma (FTC) is the second most common pediatric thyroid carcinoma, occurring in approximately 10% of cases and is more likely to metastasize to the lungs and bones [4]. PTC is typically associated with single pathogenic/likely pathogenic oncogenic variants, including mutations in BRAF, PTEN, DICER1, and RAS, as well as kinase fusions involving RET, NTRK, PAX8, and ALK. FTC is characterized by PTEN, DICER1, and RAS mutations, as well as PAX8 fusions [6]. Based largely on adult experience, the Food and Drug Administration has approved the use of tyrosine kinase inhibitors (RET and NTRK inhibitors), as well as BRAF/MEK inhibitors in patients with advanced metastatic disease, in RAI-refractory cases, or in patients where surgical resection would result in significant morbidity [2, 7]. These agents are being used with increased frequency for adjuvant and neoadjuvant therapy in select patients. In pediatrics, there is limited data and no consensus on which patients with thyroid carcinoma would benefit from these agents, the optimal time to initiate treatment, or the duration of therapy [2]. Efforts are being made within the Children's Oncology Group (COG) to bridge this knowledge gap. Given the involvement of various pediatric specialists—including oncologists, endocrinologists, surgeons, pathologists, and nuclear medicine experts—understanding current clinical practices is vital for developing future clinical trials and fostering multidisciplinary collaboration. Pediatric oncology provider survey data: A 9-question survey was sent to all 214 COG site principal investigators (PIs) with responses from 71 (33%) PIs regarding clinical practice patterns for patients ≤ 25 years diagnosed with thyroid carcinoma. A total of 50 (70%) of the responding PIs reported their institution treats patients aged ≤ 25 years with thyroid carcinoma. Most institutions report their pediatric oncologists (n = 54; 77%) are referred 0–5 patients per year, 7 (10%) institutions report 6–10 referrals, an additional 7 report 11–20 referrals, with only 2 (3%) institutions having more than 20 cases referred per year. Of those referrals, an estimated cumulative total of 130 patients had lymph node metastasis, 53 had lung metastases, 5 had bone metastases, 2 had brain metastases, with one reported “other” site of metastasis (Figure 1). Most PIs report referrals to pediatric oncology come from pediatric endocrinology (n = 45) and pediatric otolaryngology (n = 30). Notably, 17 (24%) institutions reported patients ≤ 25 years were not referred to pediatric oncology. When patients are not referred to pediatric oncology, they are instead managed by pediatric otolaryngology and endocrinology in most cases. Most referrals to pediatric oncology occur at the time of pathologic confirmation of thyroid carcinoma (n = 27). Germline and somatic genetic testing patterns vary among COG institutions. A total of 27 (41%) institutions reported performing germline testing on all patients with thyroid carcinoma, 35 (53%) performed germline testing based on clinical indications, and 4 (6%) did not perform germline testing at all. A total of 13 (22%) institutions perform somatic testing at the time of the diagnostic fine needle aspiration, 30 (50%) at the time of thyroid surgery, and 17 (28%) did not perform somatic testing at all. These findings highlight variability in referral patterns and management of pediatric thyroid carcinoma. While surgery and radioactive iodine remain the standard of care for treating pediatric thyroid carcinoma with metastasis, there is growing interest in expanding treatment and care options. This is particularly relevant for patients with metastatic disease that is not amenable to surgery given that less than 20% of patients with distant metastasis will obtain a complete response with the current standard of care. The COG/National Cancer Institute Molecular Characterization Initiative (MCI) is providing the option for paired somatic and germline testing for pediatric patients with newly diagnosed, sporadic thyroid carcinoma across all COG institutions. Locally, this may help to identify possible patients eligible for targeted therapies. Furthermore, these clinically annotated next-generation sequencing (NGS) data are being made publicly available, providing a unique opportunity to expand our understanding of the molecular genetics of pediatric thyroid carcinoma. When asked about their interest in participating in a COG-led clinical trial optimizing medical treatment for metastatic thyroid carcinoma, 42 (59%) sites responded “yes” and 23 (32%) responded “maybe”. This underscores strong collective support for the development of prospective clinical trials aimed at optimizing treatment for pediatric patients with metastatic thyroid carcinoma. This study was supported by the Children's Oncology Group NCTN Operations Center, Grant Number: U10CA180886; NCTN Statistics and Data Center, Grant Number: U10CA180886; St. Baldrick's Foundation, Grant Number: U10CA180899; US Department of Defense Translational Team Science Award: W81XWH-22-1-0654, and Alex Lemonade Stand Foundation Center of Excellence in Pediatric Drug Development. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Theodore W. Laetsch is on consulting/advisory boards for Advanced Microbubbles, AI Therapeutics, Bayer, GSK, ITM Oncologics, and Jazz Pharmaceuticals, and received research support from Bayer, Pfizer, Eli Lilly, and Exelixis. The other authors declare no conflicts of interest.

  PublisherOA PDFDOI

• Evaluation and Surgical Management of Pediatric Cutaneous Melanoma and Atypical Spitz and Non-Spitz Melanocytic Tumors (Melanocytomas): A Report From Children's Oncology Group

  Journal of Clinical Oncology · 2024 · 19 citations

  • Medicine
  • Dermatology
  • Oncology

  PURPOSE: The purpose of this study was to develop recommendations for the diagnostic evaluation and surgical management of cutaneous melanoma (CM) and atypical Spitz tumors (AST) and non-Spitz melanocytic tumors (melanocytomas) in pediatric (age 0-10 years) and adolescent (age 11-18 years) patients. METHODS: A Children's Oncology Group-led panel with external, multidisciplinary CM specialists convened to develop recommendations on the basis of available data and expertise. RESULTS: Thirty-three experts from multiple specialties (cutaneous/medical/surgical oncology, dermatology, and dermatopathology) established recommendations with supporting data from 87 peer-reviewed publications. RECOMMENDATIONS: (1) Excisional biopsies with 1-3 mm margins should be performed when feasible for clinically suspicious melanocytic neoplasms. (2) Definitive surgical treatment for CM, including wide local excision and sentinel lymph node biopsy (SLNB), should follow National Comprehensive Cancer Network Guidelines in the absence of data from pediatric-specific surgery trials and/or cohort studies. (3) Accurate classification of ASTs as benign or malignant is more likely with immunohistochemistry and next-generation sequencing. (4) It may not be possible to classify some ASTs as likely/definitively benign or malignant after clinicopathologic and/or molecular correlation, and these Spitz tumors of uncertain malignant potential should be excised with 5 mm margins. (5) ASTs favored to be benign should be excised with 1- to 3-mm margins if transected on biopsy. (6) Re-excision is not necessary if the AST does not extend to the biopsy margin(s) when complete/excisional biopsy was performed. (7) SLNB should not be performed for Spitz tumors unless a diagnosis of CM is favored on clinicopathologic evaluation. (8) Non-Spitz melanocytomas have a presumed increased risk for progression to CM and should be excised with 1- to 3-mm margins if transected on biopsy. (9) Re-excision of non-Spitz melanocytomas is not necessary if the lesion is completely excised on biopsy.

  PublisherOA PDFDOI

• EX-VIVO OOCYTE RETRIEVAL FOR FERTILITY PRESERVATION IN AN ADOLESCENT PATIENT WITH RECURRENT OVARIAN DYSGERMINOMA

  Fertility and Sterility · 2023-10-01

  articleOpen access
  PublisherOA PDFDOI

• Abstract 3898: Discovering novel therapies in the treatment of osteosarcoma

  Cancer Research · 2022

  1st authorCorresponding
  • Medicine
  • Cancer research
  • Oncology

  Abstract Introduction: This research aims to discover novel therapies in the treatment of osteosarcoma (OS). OS is the most common primary bone cancer in pediatrics. 5-year overall survival is around 70% for patients presenting with localized OS, and less than 30% for patients with relapsed or metastatic disease. OS remains difficult to cure in large part due to the heterogenous property of the tumor and high rate of somatic mutations. Methods: Using high throughput screening (HTS), 320 drugs purchased from Selleck have been tested against 3 OS cell lines - HOS, LM7, and 143B - each of which harbors different mutations seen in OS. The Echo® 650 Series Next Generation Acoustic Liquid Handler is a robotic machine used for HTS. On day -1, cells from each cell line were added to 384 well plates based on calculations from cell line density testing. On day 0, 3 drug concentrations (10uM, 1uM and 0.1uM) for 320 drugs were added to each cell line using the Echo® machine and HTS technology. On day 8, the inhibitory concentration was tested among all cell lines. Our standard for successful cell inhibition included drugs with an inhibitory concentration of ≥98% (IC98) in ≥2 drug concentrations on all 3 cell lines. Additionally, orthotopic xenograft models of immunocompromised mice have been established. 10 OS models have been implanted intratibially in mice from 5 patient samples (3 samples received from consented patients treated at Lurie Children’s Hospital, 2 samples gifted from St. Jude Children’s Research Hospital) and 5 cell lines (gifted from Texas Children’s Hospital). Results: 32 drugs exhibited an IC98 on at least 1 cell line. 14 of 320 drugs met the inclusion criteria of an IC98 on all 3 cell lines, 10 of the 14 drugs have never been reported as being effective in osteosarcoma cell inhibition. These drugs are: BRL-15572 (dihydrochloride), PH-797804, Apalutamide (ARN-509), AMG-458, Ipatasertib (GDC-0068), Mifepristone, Prucalopride, VU 0361737, Olopatadine HCl, and AZ 3146. Multiple of these agents have proven to be effective in inhibiting other cancer types/solid tumors and will be of interest for in vivo testing. 5 orthotopic xenograft murine models have successfully grown, including 1 patient tumor sample from Lurie, 1 sample from St. Jude, and 3 cell lines. All 5 of the established orthotopic xenograft models have demonstrated metastatic disease to different organs including to the lungs. Tumor growth has been confirmed through gross observation, magnetic resonance imaging, computed tomography and microscopic evaluation. Conclusion: The in vitro test results are promising and provide the groundwork to proceed with in vivo testing on orthotopic xenograft models. These models will be used for drug testing of the narrowed drug agents, with tumor growth inhibition and survival time of the drug treatment group monitored against a control group without drug exposure. Results from in vivo testing will be proposed for future clinical trials for treating pediatric osteosarcoma. Citation Format: Casey Mehrhoff, Yuchen Du, Sophie Xiao, Robert Byrd, Chris Tsz-Kwong Man, Daniele Procissi, David Walterhouse, Xiao Nan Li. Discovering novel therapies in the treatment of osteosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3898.

  PublisherDOI

• IVIG-Induced Coombs-Positive Hemolytic Anemia in a Critically Ill Adolescent Male

  PEDIATRICS · 2019-08-01

  article1st authorCorresponding

  BACKGROUND: A well-described but not universally appreciated side effect of IVIG administration is clinically apparent, sometimes severe hemolysis. We describe a severe case of Coombs-positive hemolytic anemia secondary to IVIG. IVIG is a blood derivative manufactured from pools of 5,000 to 10,000 individual plasma donations. IVIG is not ABO-type restricted, so anti-A, anti-B and anti-A,B isoagglutinins are measureable in IVIG. A number of other RBC alloantibodies to minor blood group antigens have also been detected. CASE REPORT: A 16-year-old male with PMH of OSA and obesity was admitted for adenoviral …

  PublisherDOI

• IVIG-Induced Coombs-Positive Hemolytic Anemia in a Critically Ill Adolescent Male

  PEDIATRICS · 2019-08-01

  article1st authorCorresponding
  PublisherDOI

• Factors Influencing Pediatric Emergency Department Visits for Low-Acuity Conditions

  Pediatric Emergency Care · 2018-07-16 · 37 citations

  article

  OBJECTIVES: Emergency department (ED) overcrowding is a growing problem, and pediatric patients are contributing. In this study, we aimed to determine which factors influence parents or guardians to choose the ED over their primary care physician (PCP). METHODS: A cross-sectional, online survey was administered in an academic hospital pediatric ED from September to October 2017. The 21-question survey was offered to the parents or guardians of pediatric patients triaged as low acuity. The survey assessed establishment and availability of their PCP, perception of illness or injury severity, reasons for choosing the ED, and demographic information. RESULTS: A total of 101 surveys were collected, with a 95% completion rate. Most patients had an established PCP. More than two-thirds did not attempt to contact their PCP prior to their ED visit. Nearly half stated their PCP did not offer after-hours or weekend availability. Most did not feel their child's condition was serious. Almost half would have waited to see their PCP if they could be seen within 24 hours. CONCLUSIONS: There appears to be a common misperception that PCPs do not offer extended hours. In addition, the parent or guardian's perception of severity was oftentimes more serious than perceived by medical staff. These results suggest that improving health literacy among our patient population by educating them on PCP availability and capability, ancillary services offered by PCP, and appropriate usage of the ED could potentially reduce nonurgent ED visits.

  PublisherDOI

Frequent coauthors

• Susana Puig

  Hospital Clínic de Barcelona

  10 shared

• Andrew J. Colebatch

  Royal Prince Alfred Hospital

  6 shared

• Robert S. Byrd

  Northwestern University

  4 shared

• Elena B. Hawryluk

  Harvard University

  4 shared

• Melinda Jen

  Children's Hospital of Philadelphia

  4 shared

• Raymond L. Barnhill

  Institut Curie

  4 shared

• Jennifer H. Aldrink

  Nationwide Children's Hospital

  4 shared

• Susan M. Swetter

  4 shared

Labs

• University of Utah Pediatric Hematology/OncologyPI