Oral sirolimus for the treatment of juvenile xanthogranuloma: Report of two pediatric cases.

Juvenile xanthogranuloma (JXG) with extensive cutaneous or visceral organ involvement is often associated with high morbidity and treatment commonly involves surgical excision, radiotherapy, systemic steroids, or chemotherapy. Sirolimus, a mammalian target of rapamycin (mTOR) inhibitor, is an oral antitumor and immunosuppressive therapy used to treat various neoplastic disorders, including histiocytic disorders. We report two pediatric cases of JXG successfully treated with oral sirolimus monotherapy, and postulate that sirolimus may induce rapid disease resolution and long-term remission for patients with both skin-limited and multisystemic JXG. Our findings warrant further investigation of the relationship between the mTOR pathway and JXG.

Geriatric chronic recurrent multifocal osteomyelitis (CRMO) mimicking multifocal multiple myeloma: a first in an octogenarian.

Chronic recurrent multifocal osteomyelitis (CRMO), an autoinflammatory bone disorder characterized by non-bacterial osteomyelitis causing recurrent multifocal bone lesions, is a well-known, yet uncommon pediatric condition that rarely affects adults; to date, it has never been diagnosed over the age of 75. The following report will discuss the first octogenarian diagnosed with CRMO and therefore represents an exceptionally rare presentation of a rare disease. An 83-year-old woman presented with progressive right shoulder, forearm, and hip pain, with associated weight loss and global weakness, requiring a wheelchair for mobility. Imaging revealed a pathologic right ulna fracture in addition to lytic lesions of the right proximal humerus and proximal femur. The clinical picture was thus that of a patient with probable multiple myeloma versus metastatic disease. After an extensive workup, however, the lesions were not malignant; histologic findings were instead suggestive of chronic osteomyelitis with negative cultures. Given the multifocal nature of this condition, combined with a lack of clinical symptoms of infection, a diagnosis of CRMO was rendered. The patient underwent intramedullary nailing of the right femur and splinting of the ulna, with a subsequent remarkable recovery to painless ambulation, complete union of the right ulna fracture, and resolution of the lytic lesions without receiving any targeted medical treatment. This case highlights the importance of maintaining CRMO on the differential for multifocal skeletal lesions, regardless of age. Performing a thorough workup with necessary imaging, biopsy, and culture are critical to establishing this diagnosis, which can only made as a diagnosis of exclusion.

The Use of Sunitinib as Maintenance Therapy in a Pediatric Patient With a Poorly Differentiated Thymic Carcinoma.

BACKGROUND: Thymic carcinomas are rare aggressive mediastinal tumors with a median survival of 2 years. OBSERVATION: We present a pediatric patient who was diagnosed with metastatic thymic carcinoma and showed continuous improvement of his primary mass and lung metastases with a regimen of cisplatin/docetaxel followed by long-term maintenance therapy with sunitinib for over 5 years. CONCLUSIONS: This report demonstrates a long-term positive treatment effect using chemotherapy followed by sunitinib in an advanced thymic carcinoma. We are not aware of other reports of pediatric patients with metastatic thymic carcinoma treated with sunitinib maintenance who maintained a durable response for this prolonged period of time.

Features of Intestinal Disease Associated With COVID-Related Multisystem Inflammatory Syndrome in Children.

ABSTRACT: Multisystem inflammatory syndrome in children (MIS-C) is a recently identified syndrome that appears to be temporally associated with novel coronavirus 2019 infection. MIS-C presents with fever and evidence of systemic inflammation, which can manifest as cardiovascular, pulmonary, neurologic, and gastrointestinal (GI) system dysfunction. Presenting GI symptoms are seen in the majority, including abdominal pain, diarrhea, and vomiting. Any segment of the GI tract may be affected; however, inflammation in the ileum and colon predominates. Progressive bowel wall thickening can lead to luminal narrowing and obstruction. Most will have resolution of intestinal inflammation with medical therapies; however, in rare instances, surgical resection may be required.

Benign infiltrative myofibroblastic neoplasms of childhood with USP6 gene rearrangement.

AIMS: Several morphologically overlapping (myo)fibroblastic neoplasms harbour USP6 fusions, including aneurysmal bone cysts, nodular fasciitis, myositis ossificans, cranial fasciitis, fibro-osseous pseudotumour of the digits, and cellular fibroma of the tendon sheath. USP6-induced neoplasms are almost universally benign and cured by local excision. We aim to highlight the diagnostic value of USP6 fusion detection in a series of aggressive-appearing paediatric myofibroblastic tumours. METHODS AND RESULTS: Three deep-seated, radiographically aggressive, and rapidly growing childhood myofibroblastic neoplasms were morphologically and molecularly characterised by USP6 break-apart fluorescence in-situ hybridisation (FISH), transcriptome sequencing, and targeted capture analysis. Each tumour occurred in the lower-extremity deep soft tissue of a child presenting with pain, limping, or a mass. In all three patients, imaging studies showed a solid mass that infiltrated into surrounding skeletal muscle or involved/eroded underlying bone. The biopsied tumours consisted of variably cellular myofibroblastic proliferations with variable mitotic activity that lacked overt malignant cytological features. FISH showed that all tumours had USP6 rearrangements. On the basis of these results, all three patients were treated with conservative excision with positive margins. The excised tumours had foci resembling nodular fasciitis, fibromatosis, and pseudosarcomatous proliferation. Next-generation sequencing revealed COL1A1-USP6 fusions in two tumours and a COL3A1-USP6 fusion in the third tumour. One tumour had a subclonal somatic APC in-frame deletion. No recurrence was observed during follow-up (8-40 months). CONCLUSION: We present a series of benign, but aggressive-appearing, USP6-rearranged myofibroblastic tumours. These deep-seated tumours had concerning clinical and radiographic presentations and did not fit into one distinct histological category. These cases highlight the diagnostic value of USP6 fusion detection to identify benign nondescript tumours of this group, especially those with aggressive features, to avoid overtreatment.

Congenital Hepatoblastoma and Beckwith-Wiedemann Syndrome.

Following the discovery of a fetal hepatic tumor, labor was induced at 38 weeks, and a phenotypically normal female was delivered vaginally. A serum alpha-fetoprotein level at birth was 373,170 ng/mL. Postnatal magnetic resonance imaging confirmed a mass in the right lobe of the liver, and a percutaneous core biopsy revealed an epithelial type hepatoblastoma with predominantly embryonal histology. Methylation testing revealed hypomethylation at imprinting center 2, consistent with a diagnosis of Beckwith-Wiedemann syndrome. This case suggests that Beckwith-Wiedemann syndrome testing should be considered in all patients with hepatoblastoma, even in the absence of other phenotypic stigmata.

The use of 3D printing in shared decision making for a juvenile aggressive ossifying fibroma in a pediatric patient.

Juvenile aggressive ossifying fibromas (JAOF) are rare, typically benign pediatric tumors that are locally aggressive and have high recurrence rates. A 7-year old male presented with a palatal mass and a 3D printed model was created and used as a visual aide to highlight the importance of management in terms of functional, cosmetic, and disease-free outcomes with the family. The patient ultimately underwent successful enucleation with final pathology consistent with JAOF. To our knowledge, this is the first description of the use of 3D printing to help in the shared decision-making process for the treatment of this aggressive tumor.

Intratibial Injection Causes Direct Pulmonary Seeding of Osteosarcoma Cells and Is Not a Spontaneous Model of Metastasis: A Mouse Osteosarcoma Model.

BACKGROUND: Although metastasis is the major cause of mortality in patients with osteosarcoma, little is known about how micrometastases progress to gross metastatic disease. Clinically relevant animal models are necessary to facilitate development of new therapies to target indolent pulmonary metastases. Intratibial injection of human and murine osteosarcoma cell lines have been described as orthotopic models that develop spontaneous pulmonary metastasis over time. However, there is variability in reported injection techniques and metastatic efficiency. QUESTIONS/PURPOSES: We aimed to characterize a widely used murine model of metastatic osteosarcoma, determine whether it is appropriate to study spontaneous pulmonary metastasis by establishing a reliable volume for intratibial injection, determine the incidence of primary tumor and metastatic formation, determine the kinetics of pulmonary metastatic seeding and outgrowth, and the contribution of the primary tumor to subsequent development of metastasis. METHODS: The metastatic mouse osteosarcoma cell line K7M2 was injected into the tibia of mice. The maximum volume that could be injected without leakage was determined using Evan's blue dye (n = 8 mice). Primary tumor formation and metastatic efficiency were determined by measuring the incidence of primary tumor and metastatic formation 4 weeks after intratibial injection (n = 30). The kinetics of metastatic development were determined by performing serial euthanasia at 1, 2, 3, and 4 weeks after injection (n = 24; five to six mice per group). Number of metastatic foci/histologic lung section and metastatic burden/lung section (average surface area of metastatic lesions divided by the total surface area of the lung) was calculated in a blinded fashion. To test the contribution of the primary tumor to subsequent metastases, amputations were performed 30 minutes, 4 hours, or 24 hours after injection (n = 21; five to six mice per group). Mice were euthanized after 4 weeks and metastatic burden calculated as described previously, comparing mice that had undergone amputation with control, nonamputated mice. Differences between groups were calculated using Kruskal-Wallis and one-way analysis of variance. RESULTS: The maximum volume of cell suspension that could be injected without leakage was 10 µL. Intratibial injection of tumor cells led to intramedullary tumor formation in 93% of mice by 4 weeks and resulted in detectable pulmonary metastases in 100% of these mice as early as 1 week post-injection. Metastatic burden increased over time (0.88% ± 0.58, week 1; 6.6% ± 5.3, week 2; 16.1% ± 12.5, week 3; and 40.3% ± 14.83, week 4) with a mean difference from week 1 to week 4 of -39.38 (p < 0.001; 95% confidence interval [CI], -57.39 to -21.37), showing pulmonary metastatic growth over time. In contrast, the mean number of metastatic foci did not increase from week 1 to week 4 (36.4 ± 33.6 versus 49.3 ± 26.3, p = 0.18). Amputation of the injected limb at 30 minutes, 4 hours, and 24 hours after injection did not affect pulmonary metastatic burden at 4 weeks, with amputation as early as 30 minutes post-injection resulting in a metastatic burden equivalent to tumor-bearing controls (48.9% ± 6.1% versus 40.9% ± 15.3%, mean difference 7.96, p = 0.819; 95% CI, -33.9 to 18.0). CONCLUSIONS: There is immediate seeding of the metastatic site after intratibial injection of the K7M2 osteosarcoma cell line, independent of a primary tumor. This is therefore not a model of spontaneous metastasis. CLINICAL RELEVANCE: This model should not be used to study the early components of the metastatic cascade, but rather used as an experimental model of metastasis. Improved understanding of this commonly used model will allow for proper interpretation of existing data and inform the design of future studies exploring the biology of metastasis in osteosarcoma.

Pathogenetics of alveolar capillary dysplasia with misalignment of pulmonary veins.

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) is a lethal lung developmental disorder caused by heterozygous point mutations or genomic deletion copy-number variants (CNVs) of FOXF1 or its upstream enhancer involving fetal lung-expressed long noncoding RNA genes LINC01081 and LINC01082. Using custom-designed array comparative genomic hybridization, Sanger sequencing, whole exome sequencing (WES), and bioinformatic analyses, we studied 22 new unrelated families (20 postnatal and two prenatal) with clinically diagnosed ACDMPV. We describe novel deletion CNVs at the FOXF1 locus in 13 unrelated ACDMPV patients. Together with the previously reported cases, all 31 genomic deletions in 16q24.1, pathogenic for ACDMPV, for which parental origin was determined, arose de novo with 30 of them occurring on the maternally inherited chromosome 16, strongly implicating genomic imprinting of the FOXF1 locus in human lungs. Surprisingly, we have also identified four ACDMPV families with the pathogenic variants in the FOXF1 locus that arose on paternal chromosome 16. Interestingly, a combination of the severe cardiac defects, including hypoplastic left heart, and single umbilical artery were observed only in children with deletion CNVs involving FOXF1 and its upstream enhancer. Our data demonstrate that genomic imprinting at 16q24.1 plays an important role in variable ACDMPV manifestation likely through long-range regulation of FOXF1 expression, and may be also responsible for key phenotypic features of maternal uniparental disomy 16. Moreover, in one family, WES revealed a de novo missense variant in ESRP1, potentially implicating FGF signaling in the etiology of ACDMPV.

A subset of ectomesenchymal chondromyxoid tumours of the tongue show EWSR1 rearrangements and are genetically linked to soft tissue myoepithelial neoplasms: a study of 11 cases.

AIMS: Ectomesenchymal chondromyxoid tumour (ECT) is a rare, benign intraoral neoplasm showing a predilection for the anterior dorsum of the tongue. The World Health Organization includes ECT in the pathological spectrum of soft tissue myoepithelioma. EWS RNA-binding protein 1 gene (EWSR1) rearrangement is found in 45% of cutaneous, soft tissue and bone myoepithelial neoplasms, and pleomorphic adenoma gene 1 (PLAG1) aberrations are found in 37% of EWSR1-negative soft tissue myoepitheliomas. The aim of this study was to evaluate the presence of EWSR1 and PLAG1 rearrangements in ECTs. METHODS AND RESULTS: Eleven formalin-fixed, paraffin-embedded ECTs were evaluated with fluorescence in-situ hybridization probes for EWSR1 (22q12) and PLAG1 (8q12). Among the 11 ECTs tested, three (27.3%) showed EWSR1 rearrangement in >15% of tumour cells, whereas eight (72.7%) cases did not show EWSR1 rearrangement. Eight of nine (89%) ECTs showed gain of EWSR1, probably representing gain of all or part of chromosome 22, in a varying proportion of neoplastic cells ranging between 1.4% and 27.9%. PLAG1 rearrangement was not detected in the successfully hybridized tissue sections (7/11). No correlation was observed between the molecular and histopathological findings, such as morphology of the neoplastic cells, the presence of atypia, and matrical type. CONCLUSIONS: We identified EWSR1 rearrangement in >25% of ECTs. These results suggest that some ECTs are at least genetically related to myoepithelioma of the soft parts. Finally, PLAG1 aberrations do not appear to be critical in the pathogenesis of ECT of the tongue.

Novel FUS-KLF17 and EWSR1-KLF17 fusions in myoepithelial tumors.

Myoepithelial (ME) tumors of soft tissue and bone display a heterogeneous histologic spectrum and in about half of the cases harbor EWSR1 gene rearrangements. Despite rare case reports, the prevalence of fused in sarcoma (FUS) gene abnormalities and its related fusion partners remains undetermined among ME tumors. Therefore, we screened 66 EWSR1-negative ME tumors for FUS abnormalities by fluorescence in situ hybridization (FISH). In an index FUS-rearranged case, 3'-rapid amplification of cDNA ends (RACE) was applied to identify the fusion partner. Results were further confirmed by reverse transcription-PCR, followed by FISH screening the entire cohort of FUS-rearranged and EWSR1-positive ME lesions lacking a known fusion partner. The correlation between genotype and clinicopathological features was also investigated. As a result, six (9%) FUS-rearranged cases were identified, spanning divergent age groups, tumor locations, and morphologic features. A novel FUS-KLF17 fusion was identified by 3'-RACE in an 11-year-old girl with a foot lesion associated with locoregional metastases. Three additional cases with FUS-KLF17 fusions were identified and one KLF17 rearrangement (6.3%) was found among the 16 EWSR1-positive cases tested. The KLF17-related ME tumors affected younger patients and often exhibited trabecular growth in a myxohyaline stroma, but this genotype did not correlate with a malignant phenotype. In conclusion, a small subset of ME tumors harbor FUS rearrangements, two thirds of them being associated with KLF17 fusion. FUS FISH analysis is recommended in EWSR1-negative lesions in which a ME diagnosis is suspected. KLF17 is also a rare gene fusion partner to EWSR1-rearranged ME tumors.

Recurrent NCOA2 gene rearrangements in congenital/infantile spindle cell rhabdomyosarcoma.

Spindle cell rhabdomyosarcoma (RMS) is a rare form of RMS with different clinical characteristics between children and adult patients. Its genetic hallmark remains unknown and it remains debatable if there is pathogenetic relationship between the spindle cell and the so-called sclerosing RMS. We studied two pediatric and one adult spindle cell RMS by next generation RNA sequencing and FusionSeq data analysis to detect novel fusions. An SRF-NCOA2 fusion was detected in a spindle cell RMS from the posterior neck in a 7-month-old child. The fusion matched the tumor karyotype and was confirmed by FISH and RT-PCR, which showed fusion of SRF exon 6 to NCOA2 exon 12. Additional 14 spindle cell (from 8 children and 6 adults) and 4 sclerosing (from 2 children and 2 adults) RMS were tested by FISH for the presence of abnormalities in NCOA2, SRF, as well as for PAX3 and NCOA1. NCOA2 rearrangements were found in two additional spindle cell RMS from a 3-month-old and a 4-week-old child. In the latter tumor, TEAD1 was identified by rapid amplification of cDNA ends (RACE) to be the NCOA2 gene fusion partner. None of the adult tumors were positive for NCOA2 rearrangement. Despite similar histomorphology in adults and young children, these results suggest that spindle cell RMS is a heterogeneous disease genetically as well as clinically. Our findings also support a relationship between NCOA2-rearranged spindle cell RMS occurring in young childhood and the so-called congenital RMS, which often displays rearrangements at 8q13 locus (NCOA2).

A Rare Case of Intraosseous Papillary Hemangioma of the Head and Neck.

Papillary hemangioma is a novel variant of intravascular hemangioma. It is more common in adults and has a male predominance. Most tumors reported so far are solitary and cutaneous. Here we present a rare case of an intraosseous papillary hemangioma involving the frontal bone. Brain imaging in a 69-year-old man with a slowly enlarging swelling on the right frontal area following an accidental fall demonstrated a 4.5 cm × 1.7 cm × 4.2 cm mass originating from the right frontal bone, with a tiny defect on the orbital roof. A malignant process was favored, and the mass was removed. Histopathology revealed a vascular lesion showing intraosseous distribution with foci of extension into the fibrous connective tissue. There were areas of plump endothelial cells with intracytoplasmic hyaline globules arranged in papillary configuration. The lesional cells were immunoreactive with CD34. AE1/AE3, EMA, PR, D2-40, inhibin, and S100 stains were negative. Ki-67 was low. This is the first intraosseous and second noncutaneous papillary hemangioma. Clinically it differs from other cases by the presence of trauma as a preceding event. Since its prognosis is unknown such patients should be monitored for recurrence or malignant transformation.

A 53-Year-Old With Progressive Dyspnea.

CASE PRESENTATION: A 53-year-old woman with a history of pulmonary embolism treated with rivaroxaban came to the ED after 4 days of acutely worsening dyspnea and chest pressure. On arrival, her temperature was 36.7 °C; heart rate, 71 beats/min; BP, 98/59 mm Hg; respiratory rate, 22 breaths/min; and Spo2 95% on room air. Her WBC count was elevated at 15,770/µL; hemoglobin, 13.3 g/dL; platelets, 280,000/µL; INR (international normalized ratio), elevated at 1.66; and partial thromboplastin time, elevated at 18.8 s. Serum chemistry results were unremarkable, and pro-brain natriuretic peptide was slightly elevated at 530 pg/mL (normal, < 300 pg/mL).

Chromothripsis in lipoblastoma: second reported case with complex PLAG1 rearrangement.

Lipoblastomas (LPBs) are rare benign neoplasms derived from embryonal adipose that occur predominantly in childhood. LPBs typically present with numeric or structural rearrangements of chromosome 8, the majority of which involve the pleomorphic adenoma gene 1 (PLAG1) proto-oncogene on chromosome 8q12. Here, we report on a LPB case on which showed evidence of chromothripsis. This is the second reported case of chromothripsis in LPB.

Locally Invasive Papillary Intralymphatic Angioendothelioma Arising Within a Lymphatic/Venous Malformation.

BACKGROUND Papillary intralymphatic angioendothelioma (PILA) is a rare vascular tumor affecting children and young adults, with less than 50 cases reported in the literature. This tumor typically presents in the extremities, exhibits borderline behavior, and has a prominent lymphatic phenotype. Originally thought to be malignant, PILA was later recognized for its borderline behavior and lymphatic features, leading to its current classification as a "rarely metastasizing lymphatic vascular neoplasm". CASE REPORT We present the case of a 10-year-old girl with a 6-year history of a right facial venous malformation, which was ultimately diagnosed as PILA in the background of lymphatic/venous malformation (LVM). After undergoing surgical excision of a right facial soft-tissue tumor, histopathological examination revealed scattered lymphatics and thin-walled vascular channels with blood in skeletal muscle and fibroadipose tissue. Intraluminal papillary proliferation of vascular spaces lined by cytologically bland spindle cells was observed, along with Kaposiform morphology and small-vessel proliferation. Immunohistochemical staining confirmed endothelial cell markers (D2-40, ERG, CD34, and CD31) and numerous CD3(+) lymphocytes in the lumen, surrounded by CD3(+) T lymphocytes and CD20(+) B lymphocytes in the surrounding stroma. The tumor lacked pleomorphism, significant mitotic activity, and necrosis. CONCLUSIONS PILA presents a diagnostic challenge and should be considered in the differential diagnosis of cutaneous vascular neoplasms. Long-term follow-up is crucial due to its borderline behavior and potential for local invasiveness and metastasis. Accurate diagnosis, aided by characteristic histological and immunohistochemical features, is essential for appropriate management of this rare vascular tumor.

Conservative long-term treatment of children with eosinophilic esophagitis.

BACKGROUND: Current treatments of eosinophilic esophagitis (EoE), including restrictive diets or glucocorticoids, provide only transient improvement. Proton pump inhibitor (PPI) use in EoE does not lead to histologic improvement; however, the long-term use of PPI on symptoms and prevention of complications has not been evaluated. OBJECTIVE: To evaluate the use of PPI as maintenance therapy in children with EoE. METHODS: Eosinophilic esophagitis was diagnosed based on initial endoscopic biopsies and persistent eosinophilic inflammation despite PPI therapy. Inclusion criteria included diagnosis of EoE and PPI use as primary maintenance treatment. Patients were excluded if they were treated with dietary or glucocorticoid therapy. Histologic evidence of inflammation as well as degree of subepithelial fibrosis at presentation was compared with most recent biopsies while receiving PPI therapy. RESULTS: Thirty-eight patients (30 males and 8 females; average age 6.7 ± 5.4 years) fulfilled inclusion criteria. Duration of follow-up was 3.0 ± 2.4 years. At presentation, vomiting was significantly more frequent in the younger patients, whereas dysphagia occurred more frequently in the older patients. At follow-up, 26 patients were asymptomatic, and the remaining 12 patients' symptoms were significantly improved. No complications of stricture or food impaction were seen. Significant eosinophilic inflammation persisted in 28 patients. No difference in degree of subepithelial fibrosis at diagnosis compared with most recent biopsies. The z-scores of the treated EoE patients significantly improved. CONCLUSION: Patients with EoE treated with PPIs show an improvement in symptoms and z-scores despite persistent eosinophilic inflammation. PPI treatment may be useful maintenance therapy in children with EoE.

Esophageal carcinoma in children and adolescents.

BACKGROUND: Esophageal cancer is rare in children and is limited to isolated case reports. We describe 2 cases of esophageal carcinoma (1 case each of squamous cell carcinoma and adenocarcinoma) and present literature review of esophageal carcinoma in childhood. OBSERVATIONS: Both of our patients had common symptoms of progressive dysphagia and significant weight loss at presentation. We were unable to identify any specific predisposing factors for either adenocarcinoma (caustic ingestion, reflux disease, Barrett esophagus) or squamous cell carcinoma (caustic ingestion, inherited bone marrow failure syndromes). Both patients responded poorly to chemotherapy and died of progressive disease. CONCLUSIONS: On account of the rarity of esophageal carcinoma in this age group, there are no management guidelines for the pediatric oncologist. There is a strong need for collaborative efforts between adult and pediatric oncologists to establish cooperative diagnostic and therapeutic protocols for successful management of rare pediatric tumors like esophageal carcinoma.

Solitary Pediatric Osteochondroma of the Spine With Cord Compression.

Osteochondromas typically arise in the appendicular skeleton, with axial lesions occurring less commonly. Osteochondroma of the spine resulting in cord compression and symptomatic myelopathy is relatively rare. Most cases are reported in adolescents and adults. Consequently, there is a scarcity of literature regarding its occurrence in the pediatric population. We report the case of a cervical osteochondroma of C4-6 with cord compression in a nine-year-old girl. Surgical excision with laminectomy and laminotomy successfully resolved all neurologic deficits. A literature review revealed 27 cases of pediatric osteochondromas with cord compression, suggesting that these lesions are not as rare in the pediatric population as previously thought.