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Although children and young adults with Hodgkin's lymphoma usually have a favorable prognosis, patients with primary refractory disease and some subsets of relapsed patients still have a dismal outcome. Brentuximab vedotin (BV) in combination with bendamustine may represent a suitable salvage therapy; data on 32 patients aged less than 25 years were retrospectively analyzed. Patients received up to six cycles of treatment of BV 1.8 mg/kg on day 1 and bendamustine 90–120 mg/m2 on days 2 and 3. At the end of treatment, the overall response rate was 81%. The 3-year overall and progression-free survivals are 78.1% and 67%, respectively.

Rhabdomyosarcoma (RMS) is an aggressive pediatric malignancy of the muscle, that includes Fusion Positive (FP)-RMS harboring PAX3/7-FOXO1 and Fusion Negative (FN)-RMS commonly with RAS pathway mutations. RMS express myogenic master transcription factors MYOD and MYOG yet are unable to terminally differentiate. Here, we report that SNAI2 is highly expressed in FN-RMS, is oncogenic, blocks myogenic differentiation, and promotes growth. MYOD activates SNAI2 transcription via super enhancers with striped 3D contact architecture. Genome wide chromatin binding analysis demonstrates that SNAI2 preferentially binds enhancer elements and competes with MYOD at a subset of myogenic enhancers required for terminal differentiation. SNAI2 also suppresses expression of a muscle differentiation program modulated by MYOG, MEF2, and CDKN1A. Further, RAS/MEK-signaling modulates SNAI2 levels and binding to chromatin, suggesting that the differentiation blockade by oncogenic RAS is mediated in part by SNAI2. Thus, an interplay between SNAI2, MYOD, and RAS prevents myogenic differentiation and promotes tumorigenesis.

Background Neuroblastoma (NB) is the most common, extracranial childhood solid tumor arising from neural crest progenitor cells and is a primary cause of death in pediatric patients. In solid tumors, stromal elements recruited or generated by the cancer cells favor the development of an immune-suppressive microenvironment. Herein, we investigated in NB cell lines and in NB biopsies, the presence of cancer cells with mesenchymal phenotype and determined the immune-suppressive properties of these tumor cells on natural killer (NK) cells. Methods We assessed the mesenchymal stromal cell (MSC)-like phenotype and function of five human NB cell lines and the presence of this particular subset of neuroblasts in NB biopsies using flow-cytometry, immunohistochemistry, RT-qPCR, cytotoxicity assays, western blot and silencing strategy. We corroborated our data consulting a public gene-expression dataset. Results Two NB cell lines, SK-N-AS and SK-N-BE(2)C, exhibited an unprecedented MSC phenotype (CD105 + /CD90 + /CD73 + /CD29 + /CD146 + /GD2 + /TAZ +). In these NB-MSCs, the ectoenzyme CD73 and the oncogenic/immune-regulatory transcriptional coactivator TAZ were peculiar markers. Their MSC-like nature was confirmed by their adipogenic and osteogenic differentiation potential. Immunohistochemical analysis confirmed the presence of neuroblasts with MSC phenotype (CD105 + /CD73 + /TAZ +). Moreover, a public gene-expression dataset revealed that, in stage IV NB, a higher expression of TAZ and CD105 strongly correlated with a poorer outcome. Among the NB-cell lines analyzed, only NB-MSCs exhibited multifactorial resistance to NK-mediated lysis, inhibition of activating NK receptors, signal adaptors and of NK-cell cytotoxicity through cell-cell contact mediated mechanisms. The latter property was controlled partially by TAZ, since its silencing in NB cells efficiently rescued NK-cell cytotoxic activity, while its overexpression induced opposite effects in non-NB-MSC cells. Conclusion

Tumor-infiltrating lymphocytes play an essential role in improving clinical outcome of neuroblastoma (NB) patients, but their relationship with other tumor-infiltrating immune cells in the T cell-inflamed tumors remains poorly investigated. Here we show that dendritic cells (DCs) and natural killer (NK) cells are positively correlated with T-cell infiltration in human NB, both at transcriptional and protein levels, and associate with a favorable prognosis. Multiplex imaging displays DC/NK/T cell conjugates in the tumor microenvironment of low-risk NB. Remarkably, this connection is further strengthened by the identification of gene signatures related to DCs and NK cells able to predict survival of NB patients and strongly correlate with the expression of PD-1 and PD-L1. In summary, our findings unveil a key prognostic role of DCs and NK cells and indicate their related gene signatures as promising tools for the identification of clinical biomarkers to better define risk stratification and survival of NB patients.

Retinoblastoma (RB) is the most common tumor of the eye in early childhood. Although recent advances in conservative treatment have greatly improved the visual outcome, local tumor control remains difficult in the presence of massive vitreous seeding. Traditional biopsy has long been considered unsafe in RB, due to the risk of extraocular spread. Thus, the identification of new biomarkers is crucial to design safer diagnostic and more effective therapeutic approaches. Exosomes, membrane-derived nanovesicles that are secreted abundantly by aggressive tumor cells and that can be isolated from several biological fluids, represent an interesting alternative for the detection of tumor-associated biomarkers. In this study, we defined the protein signature of exosomes released by RB tumors (RBT) and vitreous seeding (RBVS) primary cell lines by high resolution mass spectrometry. A total of 5666 proteins were identified. Among these, 5223 and 3637 were expressed in exosomes RBT and one RBVS group, respectively. Gene enrichment analysis of exclusively and differentially expressed proteins and network analysis identified in RBVS exosomes upregulated proteins specifically related to invasion and metastasis, such as proteins involved in extracellular matrix (ECM) remodeling and interaction, resistance to anoikis and the metabolism/catabolism of glucose and amino acids.

Bone marrow (BM) is the major target organ for neuroblastoma (NB) metastasis and its involvement is associated with poor outcome. Yet, the mechanism by which NB cells invade BM is largely unknown. Tumour microenvironment represents a key element in tumour progression and mesenchymal stromal cells (MSCs) have been recognized as a fundamental part of the associated tumour stroma. Here, we show that BM-MSCs isolated from NB patients with BM involvement exhibit a greater osteogenic potential than MSCs from non-infiltrated BM. We show that BM metastasis-derived NB-cell lines secrete higher levels of exosomal miR-375, which promotes osteogenic differentiation in MSCs. Of note, clinical data demonstrate that high level of miR-375 correlates with BM metastasis in NB patients. Our findings suggest, indeed, a potential role for exosomal miR-375 in determining a favourable microenvironment in BM to promote metastatic progression. MiR-375 may, thus, represent a novel biomarker and a potential target for NB patients with BM involvement.

Immunomodulating agents such as anti–programmed cell death protein 1 (PD-1) have recently gained a crucial role in the treatment of numerous human malignant tumors.1 Cemiplimab is a novel PD-1 blocker approved for the treatment of locally advanced or metastatic cutaneous squamous cell carcinoma (cSCC) in patients who are not candidates for curative surgery or radiation.2 During the last few years, other anti–PD-1 agents such as pembrolizumab and nivolumab have occasionally been used off-label to manage cases of advanced cSCC.3 We describe 1 patient with recessive dystrophic epidermolysis bullosa (RDEB) and multiple cSCCs who was successfully treated with pembrolizumab.

Aim: Desmoplastic small round cell tumor (DSRCT) is a rare, aggressive mesenchymal tumor, lacking biomarkers for diagnosis, treatment stratification and prognosis. We investigated the exosomal miRNA profile in plasma samples collected from DSRCT patients, evaluating their potential as circulating biomarkers for this tumor. Patients & methods: We isolated exosomes from plasma of three DSRCT adolescents and four age-matched healthy controls; expression of circulating miRNAs was quantified by qPCR. Results: We identified 55 miRNAs significantly modulated compared with healthy controls. Among these miRNAs, 14 were highly dysregulated in at least one patient and 5 were expressed in all patients. Conclusion: To our knowledge, this is the first report describing exosomal miRNAs as promising biomarkers to characterize disease status in DSRCT patients.

Kabuki syndrome (KS) is an extremely rare genetic disorder, mainly caused by germline mutations at specific epigenetic modifier genes, including KMT2D. Because the tumor suppressor gene KMT2D is also frequently altered in many cancer types, it has been suggested that KS may predispose to the development of cancer. However, KS being a rare disorder, few data are available on the incidence of cancer in KS patients. Here, we report the case of a 5-year-old boy affected by KS who developed Burkitt lymphoma (BL). Genetic analysis revealed the presence of a novel heterozygous mutation in the splice site of the intron 4 of KMT2D gene in both peripheral blood-extracted DNA and tumour cells. In addition, the tumour sample of the patient was positive for the classical somatic chromosomal translocation t(8;14) involving the c-MYC gene frequently identified in BL. We propose that the mutated KMT2D gene contributes to the development of both KS and BL observed in our patient and we suggest that strict surveillance must be performed in KS patients.

Osteosarcoma is the most common malignant bone tumor in children and young adults. The identification of proteins which exhibit different subcellular localization in low- versus high-risk osteosarcoma can be instrumental to obtain prognostic information and to develop innovative therapeutic strategies. Beside the well-characterized membrane and cytoplasmic localization of Src protein, this study evaluated the prognostic relevance of its so-far unknown nuclear compartmentalization. We analyzed the subcellular distribution of total and activated (pY418) Src in a tissue microarray including 60 osteosarcoma samples. Immunohistochemical analyses revealed a variable pattern of Src expression and localization, ranging from negative to high-stained nuclei combined with a substantial cytoplasmic staining for total and activated forms. The analysis of Kaplan–Meier survival curves in relationship to the diverse permutations of cytoplasmic and nuclear staining suggested a correlation between Src subcellular localization and the overall survival (OS) of osteosarcoma patients. In order to explain this different subcellular localization, normal osteoblasts and three osteosarcoma cell lines were used to investigate the molecular mechanism. Once confirmed a variable Src localization also in these cell lines, we demonstrated a correlation between the N-myristoyltransferase enzymes expression and activity and the Src nuclear content. In conclusion, these results described a so-far unknown Src nuclear localization in osteosarcoma cells, suggesting that the combined detection of nuclear and cytoplasmic Src levels can be used as a prognostic marker for osteosarcoma patient survival. A correlation between the N-myristoyltransferase enzymes and the Src subcellular localization was described as well.

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BACKGROUND: Primary melanocytic neoplasms are rare in the pediatric age. Among them, the pattern of neoplastic meningitis represents a peculiar diagnostic challenge since neuroradiological features may be subtle and cerebrospinal fluid analysis may not be informative. Clinical misdiagnosis of neoplastic meningitis with tuberculous meningitis has been described in few pediatric cases, leading to a significant delay in appropriate management of patients. We describe the case of a child with primary leptomeningeal melanoma (LMM) that was initially misdiagnosed with tuberculous meningitis. We review the clinical and molecular aspects of LMM and discuss on clinical and diagnostic implications. CASE PRESENTATION: A 27-month-old girl with a 1-week history of vomiting with mild intermittent strabismus underwent Magnetic Resonance Imaging, showing diffuse brainstem and spinal leptomeningeal enhancement. Cerebrospinal fluid analysis was unremarkable. Antitubercular treatment was started without any improvement. A spinal intradural biopsy was suggestive for primary leptomeningeal melanomatosis. Chemotherapy was started, but general clinical conditions progressively worsened and patient died 11 months after diagnosis. Molecular investigations were performed post-mortem on tumor tissue and revealed absence of BRAF(V600E), GNAQ(Q209) and GNA11(Q209) mutations but the presence of a NRAS(Q61K) mutation. CONCLUSIONS: Our case adds some information to the limited experience of the literature, confirming the presence of the NRAS(Q61K) mutation in children with melanomatosis. To our knowledge, this is the first case of leptomeningeal melanocytic neoplasms (LMN) without associated skin lesions to harbor this mutation. Isolated LMN presentation might be insidious, mimicking tuberculous meningitis, and should be suspected if no definite diagnosis is possible or if antitubercular treatment does not result in dramatic clinical improvement. Leptomeningeal biopsy should be considered, not onl

Silicone oil is used for complicated retinal detachment, but it can be associated with relevant side effects. We report a 6-year-old South American female admitted to our hospital with steroid-resistant Fisher-Evans syndrome. She also had developed a retinal detachment, managed with intravitreal oil injection. During treatment for Fisher-Evans syndrome, she progressively developed recurrent and refractory bronchospasm, peaks of hypereosinophilia and orbital soft-tissue swelling. Despite the persistent negativity of all microbiologic tests, she was treated empirically with antibiotics. Failure of the treatment led to the execution of a biopsy of the periocular tissue that revealed an intense polymorphous infiltrate constituted by numerous monoclonal population (FR2 monoclonality) of plasma-cells. A diagnosis of lymphoma with plasmacytoid differentiation was suspected and cytotoxic treatment was started without response. For the appearance of swelling in left parotid and laterocervical region, an excisional biopsy was performed and a diagnosis of granulomatous reaction to ocular implant of silicone oil was made. In consideration of the clinical evolution, enucleation was considered, but parents did not consent to the procedure until the child developed cerebral lesions suspected to be silicone localizations. After enucleation, eosinophilic count normalized and the child no longer presented any new episode of fever or swelling. CONCLUSIONS: In this patient a granulomatous reaction is present at distance from the site of oil injection. This case suggests caution in using this substance even in ocular diseases, especially in immunocompromised patients.

OBJECTIVE: To report on the particular imaging features and high success rate of cold mode radio-frequency thermal ablation (RFTA) as the treatment of choice for intramedullary osteoid osteoma. MATERIALS AND METHODS: The study population consisted of 51 patients (39 males, 12 females; mean age 7.2 years; 11 patients under 6 years of age, including 7 males and 4 females) who underwent RFTA for osteoid osteoma and were retrospectively observed. The affected sites were the tibia (n = 22, 43%), femur (n = 13, 25%), pelvis (n = 5, 10%), anklebone (n = 3, 6%), humerus (n = 2, 4%), sacrum (n = 2, 4%), heel, radium, patella ,and rib (n = 1, 2%), respectively. Three patients had tibial intramedullary osteoid osteoma (14% of the tibial lesions, 6% of all cases). Cold mode RFTA was performed for these three patients to obtain a large ablation area without positioning two probes. The noncooled mode was used to treat cortical and subperiosteal lesions. RESULTS: Following RFTA, all patients were pain-free and in good clinical condition. In the intramedullary osteoid osteoma group, no recurrences were observed during the 24-month follow-up period, but one patient, who was affected by cortical osteoid osteoma, required two RFTA treatments to heal completely. CONCLUSION: Children less than 6 years of age with recurrent nocturnal pain and limb swelling should be investigated for intramedullary osteoid osteoma. Once confirmed, CT-guided RFTA should be the first treatment for intramedullary osteoid osteomas because of the high success rate and reduced invasivity, especially with cold mode RFTA. The outcome is related to the disappearance of pain, and the efficacy may be checked shortly after treatment with MR imaging to evaluate the absence of lesion in the ablation area.