Lung metastasis is the major cause of death in osteosarcoma patients. However, molecular mechanisms underlying this metastasis remain poorly understood. To identify key molecules related with pulmonary metastasis of pediatric osteosarcomas, we analyzed high‐throughput miRNA expression in a cohort of 11 primary tumors and 15 lung metastases. Results were further validated with an independent cohort of 10 primary tumors and 6 metastases. In parallel, we performed immunohistochemical analysis of activated signaling pathways in 36 primary osteosarcomas. Only phospho‐AKT associated with lower overall survival in primary tumors, supporting its role in osteosarcoma progression. CTNNB1 expression also associated with lower overall survival but was not strong enough to be considered an independent variable. Interestingly, miR‐200c was overexpressed in lung metastases, implicating an inhibitory feed‐back loop to PI3K‐AKT. Moreover, transfection of miR200c‐mimic in U2‐OS cells reduced phospho‐AKT levels but increased cellular migration and proliferation. Notably, miR‐200c expression strongly correlated with miR‐141 and with the osteogenic inhibitor miR‐375, all implicated in epithelial to mesenchymal transition. These findings contrast epithelial tumors where reduced miR‐200c expression promotes metastasis. Indeed, we noted that osteosarcoma cells in the lung also expressed the epithelial marker CDH1, revealing a change in their mesenchymal phenotype. We propose that miR‐200c upregulation occurs late in osteosarcoma progression to provide cells with an epithelial phenotype that facilitates their integration in the metastatic lung niche. Thus, our findings identify phospho‐AKT in the primary tumor and miR‐200c later during tumor progression as prognostic molecules and potential therapeutic targets to prevent progression and metastasis of pediatric osteosarcomas.

Testicular tumours are rare in children. Painless scrotal mass is the most frequent clinical presentation. Tumoural markers (alpha-fetoprotein, beta-human gonadotropin chorionic) and hormone levels (testosterone) contribute to the diagnosis and management of a testicular mass in boys. Ultrasonography is the best imaging modality to study testicular tumours. A benign tumour is suggested when ultrasonography shows a mainly cystic component, well-defined borders, echogenic rim or normal to increased echogenicity lesion when compared to the healthy testicular parenchyma. Malignant tumour is suspected when ultrasonography shows inhomogeneous, hypoechoic, not well-circumscribed or diffuse infiltration lesion. However, these ultrasonographic findings may overlap. Colour Doppler, power Doppler, elastography and contrast-enhanced ultrasonography are useful complementary methods to characterise the focal testicular lesions. Chest computerised tomography and abdominopelvic magnetic resonance are necessary to establish the extension in case of malignant proved tumours.Benign tumours are more frequent in prepuberal boys and malignant tumours in pubertal boys. Mature teratoma prepubertal-type is the most common histologic type. Testicular sparing surgery is the choice in benign tumours. Radical inguinal orchiectomy is indicated in malignant tumours. Prognostic is excellent.The purpose of our study is to show an approach to the diagnosis and management of the most frequent testicular tumours in children according to clinical manifestations, imaging findings and tumour markers levels based on histologically confirmed tumours in our hospital.

Background T‐cell lymphoblastic lymphoma (T‐LBL) is an aggressive neoplasm closely related to T‐cell acute lymphoblastic leukaemia (T‐ALL). Despite their similarities, and contrary to T‐ALL, studies on paediatric T‐LBL are scarce and, therefore, its molecular landscape has not yet been fully elucidated. Thus, the aims of this study were to characterize the genetic and molecular heterogeneity of paediatric T‐LBL and to evaluate novel molecular markers differentiating this entity from T‐ALL. Procedure Thirty‐three paediatric T‐LBL patients were analyzed using an integrated approach, including targeted next‐generation sequencing, RNA‐sequencing transcriptome analysis and copy‐number arrays. Results Copy number and mutational analyses allowed the detection of recurrent homozygous deletions of 9p/CDKN2A (78%), trisomy 20 (19%) and gains of 17q24‐q25 (16%), as well as frequent mutations of NOTCH1 (62%), followed by the BCL11B (23%), WT1 (19%) and FBXW7, PHF6 and RPL10 genes (15%, respectively). This genetic profile did not differ from that described in T‐ALL in terms of mutation incidence and global genomic complexity level, but unveiled virtually exclusive 17q25 gains and trisomy 20 in T‐LBL. Additionally, we identified novel gene fusions in paediatric T‐LBL, including NOTCH1–IKZF2, RNGTT–SNAP91 and DDX3X–MLLT10, the last being the only one previously described in T‐ALL. Moreover, clinical correlations highlighted the presence of Notch pathway alterations as a factor related to favourable outcome. Conclusions In summary, the genomic landscape of paediatric T‐LBL is similar to that observed in T‐ALL, and Notch signaling pathway deregulation remains the cornerstone in its pathogenesis, including not only mutations but fusion genes targeting NOTCH1.

Prognostic factors and long-term survival are similar to those previously described. Reduction of global time interval to resumption of chemotherapy as well as a more specific and validated definition of pulmonary metastases at diagnosis are needed.

Background: Understanding pediatric cancer biology is a huge challenge in continuous development that is currently being implemented into the clinical practice thanks to the new high throughput technologies integrated by personalized medicine. We present the results of the Precision Medicine program for children and adolescents with solid tumors in relapse/progression carried out in University La Fe Hospital (Valencia) from 2014. This is the first Spanish experience in precision medicine published in pediatric oncology. Methods: Study enrollment was offered to all patients having a refractory or relapsed solid tumor and an available biopsy treated in La Fe Hospital (Valencia, Spain) or in other Spanish pediatric oncologic center. Eighty four patients were finally studied. The commercial Human Comprehensive Cancer GeneReadDNAseq Targeted genes Panel (Qiagen©) was sequenced in fresh/frozen samples. Variants considered pathogenic or likely pathogenic were classified using the algorithm published by Parsons et al. based on perceived clinical utility. Results: Thirteen of 84 patients (15%) received therapeutic recommendations due to an actionable variant detected and three patients received prognosis information based on sequencing results. Conclusions: Precision medicine projects based on targetable gene panel approximations can obtain translatable information to pediatric patients with reasonable efforts. This approach lowers economic expenses and reduces time of response with respect to whole exome sequencing. Since the translation to the clinical practice is the main objective of these projects, limiting the number of relatively well-known biological markers will allow us to transfer similar amount of information with less economic and human effort.