Since the original description of pathogenic germline DICER1 variation underlying PPB, the spectrum of extrapulmonary neoplasms known to be associated with DICER1 has continued to expand and now includes tumors of the ovary, thyroid, kidney, eye and brain among other sites. This report documents our experience with another manifestation: a primitive sarcoma that resembles PPB and DICER1 -associated sarcoma of the kidney. These tumors are distinguished by their unusual location in the peritoneal cavity, associated with visceral and/or parietal mesothelium. A total of seven cases were identified through pathology review in children presenting at a median age of 13 years (range 3 to 14 years). Primary sites of origin included the Fallopian tube (4 cases), serosal surface of the colon (one case), and pelvic sidewall (2 cases). One case had pathologic features of type I PPB, another type Ir (regressed) PPB and the remaining 5 had features of type II or III PPB with a mixed primitive sarcomatous pattern with or without cystic elements. All had a pathogenic DICER1 variation identified in germline and/or tumor DNA. PPB-like peritoneal tumors represent a newly described manifestation of DICER1 pathogenic variation whose pathologic features are also recapitulated in DICER1 -related renal sarcoma, cervical embryonal rhabdomyosarcoma, and some Sertoli-Leydig cell tumors with heterologous elements. Tumors arising from the Fallopian tube or elsewhere in the abdomen/pelvis, especially those with heterogeneous rhabdomyosarcomatous and/or cartilaginous differentiation, should prompt consideration of germline and tumor DICER1 testing.

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Congenital central hypoventilation syndrome (CCHS) is a rare genetic disorder affecting respiratory control and autonomic nervous system function caused by variants in the paired-like homeobox 2B ( PHOX2B ) gene. Although most patients are diagnosed in the newborn period, an increasing number of patients are presenting later in childhood, adolescence, and adulthood. Despite hypoxemia and hypercapnia, patients do not manifest clinical features of respiratory distress during sleep and wakefulness. CCHS is a lifelong disorder. Patients require assisted ventilation throughout their life delivered by positive pressure ventilation via tracheostomy, noninvasive positive pressure ventilation, and/or diaphragm pacing. At different ages, patients may prefer to change their modality of assisted ventilation. This requires an individualized and coordinated multidisciplinary approach. Additional clinical features of CCHS that may present at different ages and require periodic evaluations or interventions include Hirschsprung’s disease, gastrointestinal dysmotility, neural crest tumors, cardiac arrhythmias, and neurodevelopmental delays. Despite an established PHOX2B genotype and phenotype correlation, patients have variable and heterogeneous clinical manifestations requiring the formulation of an individualized plan of care based on collaboration between the pulmonologist, otolaryngologist, cardiologist, anesthesiologist, gastroenterologist, sleep medicine physician, geneticist, surgeon, oncologist, and respiratory therapist. A comprehensive multidisciplinary approach may optimize care and improve patient outcomes. With advances in CCHS management strategies, there is prolongation of survival necessitating high-quality multidisciplinary care for adults with CCHS.

An activating point mutation of the c-KIT tyrosine kinase receptor gene, D816H, has been described in germ cell tumors (GCTs). We report an adolescent diagnosed with an ovarian mixed GCT and systemic mastocytosis with chronic myelomonocytic leukemia (SM-CMML). The teratoma and dysgerminoma differed by copy number aberrations via single nucleotide polymorphism (SNP) microarray, but were inclusive of the same c-KIT D816H point mutation (c.2446G>C) also identified in blood and bone marrow mast cells. These findings indicate not only a clonal origin of the GCT and hematologic malignancy, but also suggest a rare KIT mutation may be playing a fundamental role in malignancy development.

PURPOSE Profiling of pediatric cancers through deep sequencing of large gene panels and whole exomes is rapidly being adopted in many clinical settings. However, the most impactful approach to genomic profiling of pediatric cancers remains to be defined. METHODS We conducted a prospective precision medicine trial, using whole-exome sequencing of tumor and germline tissue and whole-transcriptome sequencing (RNA Seq) of tumor tissue to characterize the mutational landscape of 127 tumors from 126 unique patients across the spectrum of pediatric brain tumors, hematologic malignancies, and extracranial solid tumors. RESULTS We identified somatic tumor alterations in 121/127 (95.3%) tumor samples and identified cancer predisposition syndromes on the basis of known pathogenic or likely pathogenic germline mutations in cancer predisposition genes in 9/126 patients (7.1%). Additionally, we developed a novel scoring system for measuring the impact of tumor and germline sequencing, encompassing therapeutically relevant genomic alterations, cancer-related germline findings, recommendations for treatment, and refinement of risk stratification or prognosis. At least one impactful finding from the genomic results was identified in 108/127 (85%) samples sequenced. A recommendation to consider a targeted agent was provided for 82/126 (65.1%) patients. Twenty patients ultimately received therapy with a molecularly targeted agent, representing 24% of those who received a targeted agent recommendation and 16% of the total cohort. CONCLUSION Paired tumor/normal whole-exome sequencing and tumor RNA Seq of de novo or relapsed/refractory tumors was feasible and clinically impactful in high-risk pediatric cancer patients.

PURPOSE Pleuropulmonary blastoma (PPB) is the most common primary lung neoplasm of infancy and early childhood. Type II and type III PPB have historically been associated with a poor prognosis. METHODS Patients with known or suspected PPB were enrolled in the International PPB/ DICER1 Registry. Medical records were abstracted with follow-up ascertained annually. All PPB diagnoses were confirmed by central pathology review. Beginning in 2007, the IVADo regimen (ifosfamide, vincristine, actinomycin-D, and doxorubicin) was recommended as a potential treatment regimen for children with type II and type III PPB. This regimen was compared with a historical control cohort. RESULTS From 1987 to 2021, 314 children with centrally confirmed type II and type III PPB who received upfront chemotherapy were enrolled; 132 children (75 with type II and 57 with type III) received IVADo chemotherapy. Adjusted analyses suggest improved overall survival for children treated with IVADo in comparison with historical controls with an estimated hazard ratio of 0.65 (95% CI, 0.39 to 1.08). Compared with localized disease, distant metastasis at diagnosis was associated with worse PPB event-free survival and overall survival with hazard ratio of 4.23 (95% CI, 2.42 to 7.38) and 4.69 (95% CI, 2.50 to 8.80), respectively. CONCLUSION The use of IVADo in children with type II and type III PPB resulted in similar-to-improved outcomes compared with historical controls. Inferior outcomes with metastatic disease suggest the need for novel therapies. This large cohort of uniformly treated children with advanced PPB serves as a benchmark for future multicenter therapeutic studies for this rare pediatric tumor.

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is the most common primary pediatric hepatic malignancy. 1 Surgical resection and cisplatin-based chemotherapy (CTH) form the foundation of treatment. 2 Patients with pure fetaltype histology (PFH), a minority, are able to undergo surgical resection alone. 3 The morbidity associated with both CTH and resection can be prohibitive in patients with comorbidities such as pulmonary hypertension (PHTN), who are unable to tolerate the large fluid volumes that accompany standard CTH regimens and are at high risk of cardiovascular collapse during resection. Here, we report a case of a child with PFH HB and severe PHTN treated with percutaneous image-guided microwave ablation (MWA) as sole therapy. A 14-month-old girl with a complex past medical history (Table 1), including trisomy 18, unrepaired cardiac shunts, and severe PHTN, was incidentally found to have an elevated alpha-fetoprotein (AFP) of