Is magnetic resonance imaging reliable for assessing osteosarcoma of the knee joint in children?

INTRODUCTION: The study of tumor extension in knee osteosarcomas is an essential diagnostic tool that helps determine the surgical approach. Magnetic resonance imaging (MRI) is the key component in this decision-making process, but the interpretation of signals can be difficult because peritumoral edema and inflammation may be mistaken for the tumor. HYPOTHESIS: There is a discrepancy between MRI and histopathology findings in the assessment of joint involvement in pediatric osteosarcomas of the knee. MATERIALS AND METHODS: All children who underwent an extra-articular resection for an osteosarcoma of the knee between 2007 and 2016 were included. This was indicated if there was at least one of the following MRI signs: presence of articular effusion, involvement of either the peripheral capsuloligamentous structures, central pivot or patella, or lesion abutting the articular cartilage. RESULTS: Nine patients were operated on with a mean age of 13±2.7 years. There were at least two of the described signs, mainly the involvement of the peripheral capsuloligamentous structures (78%) and central pivot (56%). The histopathology confirmed that the resection margins were healthy in all cases, but the indication for extra-articular resection could have been avoided in 89% of them. DISCUSSION: MRI is the current gold standard for assessing tumor extension, but the signs contraindicating the transarticular approach remain poorly defined. Joint effusion detected by clinical or radiological assessment is the least reliable one. It seems that the tumor's proximity to the articular cartilage, as long as there is no loss of continuity in the latter, or its extension into the central pivot should no longer be considered as relevant signs. The involvement of the peripheral capsuloligamentous structure remains an indication criterion because oncologic resection is otherwise impossible, and the risk of false-negative histopathologic diagnoses is higher. Other MRI sequences could better assess the true extension into the joint space. LEVEL OF EVIDENCE: IV, retrospective study.

Soluble CD89 is a critical factor for mesangial proliferation in childhood IgA nephropathy.

Childhood IgA nephropathy (IgAN) includes a wide spectrum of clinical presentations, from isolated hematuria to acute nephritis with rapid loss of kidney function. In adults, IgAN is an autoimmune disease and its pathogenesis involves galactose deficient (Gd) IgA1, IgG anti-Gd-IgA1 autoantibodies and the soluble IgA Fc receptor (CD89). However, implication of such factors, notably soluble CD89, in childhood IgAN pathogenesis remains unclear. Here, we studied these biomarkers in a cohort of 67 patients with childhood IgAN and 42 pediatric controls. While Gd-IgA1 was only moderately increased in patient plasma, levels of circulating IgA complexes (soluble CD89-IgA and IgG-IgA) and free soluble CD89 were markedly increased in childhood IgAN. Soluble CD89-IgA1 complexes and free soluble CD89 correlated with proteinuria, as well as histological markers of disease activity: mesangial, endocapillary hypercellularity and cellular crescents. Soluble CD89 was found in patient's urine but not in urine from pediatric controls. Mesangial deposits of soluble CD89 were detected in biopsies from patients with childhood IgAN. Serum chromatographic fractions containing covalently linked soluble CD89-IgA1 complexes or free soluble CD89 from patients induced mesangial cell proliferation in vitro in a soluble CD89-dependent manner. Recombinant soluble CD89 induced mesangial cell proliferation in vitro which was inhibited by free soluble recombinant CD71 (also a mesangial IgA receptor) or mTOR blockers. Interestingly, injection of recombinant soluble CD89 induced marked glomerular proliferation and proteinuria in mice expressing human IgA1. Thus, free and IgA1-complexed soluble CD89 are key players in mesangial proliferation. Hence, our findings suggest that soluble CD89 plays an essential role in childhood IgAN pathogenesis making it a potential biomarker and therapeutic target.

Adrenal ganglioneuromas: a retrospective multicentric study of 104 cases from the COMETE network.

OBJECTIVE: Adrenal ganglioneuromas are rare, differentiated, neuroblastic tumors that originate from the peripheral sympathetic nervous system. Because of their rarity, information is limited, derived from small cases series. Our objective was to characterize this tumor and provide help for its management. METHODS: A retrospective multicenter analysis of adrenal ganglioneuromas from 20 French centers belonging to the COMETE network and one Belgian center. RESULTS: Among the 104 cases identified, 59.6% were women (n = 62/104), median age at diagnosis was 29 years, with 24 pediatric cases. 60.6% (n = 63/104) were incidentalomas. Ganglioneuromas were non-secreting tumors in 90.8% of cases (n = 89/98), whereas the preoperative hormonal evaluation was indeterminate for 9.2% of patients (n = 9/98). CT imaging, performed on 96 patients, revealed large tumors (median diameter of 50 mm) with a non-contrast density > 10 Hounsfield units in 98.1% (n = 52/53) and calcifications in 64.6% of cases (n = 31/48). Increased uptake on 123I-MIBG scintigraphy and 18F-FDG-PET/CT was observed in 26.7% (n = 8/30) and 42.2% (n = 19/45) of the tumors, respectively. All 104 patients underwent surgery. No recurrence was observed among the 42 patients who had an imaging follow-up (mean 29.6 months, median 18 months (4-156)). CONCLUSION: Adrenal ganglioneuromas are large tumors, mostly nonfunctioning, without benign imaging features. Although the duration of follow-up was limited in our series, no recurrence was identified. A review of the literature confirms the absence of postoperative recurrence. Based on all available data, in the absence of special circumstances (genetic form, uncertain histological diagnosis), long-term follow-up is not necessary after complete surgery for patients with an adrenal ganglioneuroma.

A variant of ASIC2 mediates sodium retention in nephrotic syndrome.

Idiopathic nephrotic syndrome (INS) is characterized by proteinuria and renal sodium retention leading to edema. This sodium retention is usually attributed to epithelial sodium channel (ENaC) activation after plasma aldosterone increase. However, most nephrotic patients show normal aldosterone levels. Using a corticosteroid-clamped (CC) rat model of INS (CC-PAN), we showed that the observed electrogenic and amiloride-sensitive Na retention could not be attributed to ENaC. We then identified a truncated variant of acid-sensing ion channel 2b (ASIC2b) that induced sustained acid-stimulated sodium currents when coexpressed with ASIC2a. Interestingly, CC-PAN nephrotic ASIC2b-null rats did not develop sodium retention. We finally showed that the expression of the truncated ASIC2b in the kidney was dependent on the presence of albumin in the tubule lumen and activation of ERK in renal cells. Finally, the presence of ASIC2 mRNA was also detected in kidney biopsies from patients with INS but not in any of the patients with other renal diseases. We have therefore identified a variant of ASIC2b responsible for the renal Na retention in the pathological context of INS.

Rare Collagenous Heterozygote Variants in Children With IgA Nephropathy.

INTRODUCTION: Childhood IgA nephropathy (cIgAN) is a primary glomerulonephritis clinically characterized by microscopic hematuria and proteinuria, the presence of which may potentially overlap with Alport syndrome. Interestingly, earlier studies suggested that familial IgAN could be linked to the chromosome 2q36 region, also the coding region for collagen type 4 alpha 3/4 (COL4A3/A4). METHODS: To investigate a possible relationship or phenocopy between Alport syndrome and cIgAN, COL4A3, COL4A4, and COL4A5 exons were sequenced in 36 cIgAN patients. Clinical data and treatment were collected retrospectively. COL4A3/A4/A5 variants were classified according to American College of Medical Genetics and the Association for Molecular Pathology (ACMG/AMP) guidelines. RESULTS: Four of 36 cIgAN patients were affected by ACMG class 4/5 COL4A3 heterozygous variants (COL4A3-cIgAN). We found no COL4A4 or COL4A5 variant. Despite having rare and deleterious COL4A3 variants, 3 of 4 COL4A3-cIgAN children developed clinical and biologic features of active IgAN rather than Alport syndrome. Response to intensive immunosuppressive treatment was favorable, leading to a reduction of endocapillary and extracapillary proliferation lesions. High levels of immune immunoglobulin G and A (IgG/IgA) complexes, reduction of proteinuria, and gradual stabilization of estimated glomerular filtration rate (eGFR) argued against Alport syndrome. Nevertheless, COL4A3-cIgAN patients seemed predisposed to a more serious IgAN presentation compared with the non‒COL4A3-cIgAN group, with more glomerulosclerosis and a lower eGFR over time. One of the 4 patients underwent kidney transplant with subsequent IgAN recurrence. CONCLUSIONS: Predisposition factors for developing serious cIgAN flare-up should be considered for cIgAN with COL4A3 pathologic heterozygous variants. COL4A3 variants, usually responsible for Alport syndrome in adults, should not automatically exclude an immunosuppressive regimen in cIgAN. Moreover, evidence of an ACMG class 4/5 COL4A3 variant in early-stage cIgAN could be a helpful tool for stratifying severity of cIgAN beyond the Oxford classification.

SRY-negative 46,XX testicular/ovotesticular DSD: Long-term outcomes and early blockade of gonadotropic axis.

OBJECTIVE: SRY-negative 46,XX testicular and ovotesticular disorders/differences of sex development (T/OTDSD) represent a very rare and unique DSD condition where testicular tissue develops in the absence of a Y chromosome. To date, very few studies have described the phenotype, clinical and surgical management and long-term outcomes of these patients. Particularly, early blockade of the gonadotropic axis in patients raised in the female gender to minimize postnatal androgenization has never been reported. DESIGN: Retrospective description of sixteen 46,XX T/OTDSD patients. RESULTS: Sixteen 46,XX SRY-negative T/OTDSD were included. Most (12/16) were diagnosed in the neonatal period. Sex of rearing was male for six patients and female for ten, while the clinical presentation varied, with an external masculinization score from 1 to 10. Five patients raised as girl were successfully treated with GnRH analog to avoid virilization during minipuberty. Ovotestes/testes were found bilaterally for 54% of the patients and unilaterally for the others (with a contralateral ovary). Gonadal surgery preserved appropriate tissue in the majority of cases. Spontaneous puberty occurred in two girls and one boy, while two boys required hormonal induction of puberty. One of the girls conceived spontaneously and had an uneventful pregnancy. DNA analyses (SNP-array, next-generation sequencing and whole-exome sequencing) were performed. A heterozygous frameshit mutation in the NR2F2 gene was identified in one patient. CONCLUSIONS: This study presents a population of patients with 46,XX SRY-negative T/OTDSD. Early blockade of gonadotropic axis appears efficient to reduce and avoid further androgenization in patients raised as girls.

Transformation of a low-grade follicular lymphoma into a composite lymphoma combining a high-grade B-cell lymphoma and a lymphoblastic neoplasm expressing Terminal deoxynucleotidyl Transferase: a case report.

BACKGROUND: High-grade B-cell lymphoma with rearrangements of MYC and BCL2 and/or BCL6 is an aggressive mature B-cell neoplasm, whereas B-lymphoblastic lymphoma is immature cell proliferation, with a frequent positivity for terminal deoxynucleotidyl transferase. The transformation of a low-grade follicular lymphoma into a lymphoblastic neoplasm expressing terminal deoxynucleotidyl transferase is a very rare event. CASE PRESENTATION: A 55-year-old Caucasian man was followed for a grade 1-2 follicular lymphoma carrying a t(14;18) IGH/BCL2+ and was initially treated with R-CHOP. The follicular lymphoma presented two relapses. In the third relapse, the patient had multiple lymphadenopathy and ascites, which motivated a retroperitoneal biopsy and an ascitic tap. These samples were analyzed by histological, cytological, flow cytometric, cytogenetic, and molecular assessments. The patient died of a multiple organ dysfunction syndrome 2 weeks after his third relapse. The biopsy revealed a diffuse proliferation made up of two types of tumor cells: centroblasts (Bcl-6-positive) and immature cells (terminal deoxynucleotidyl transferase-positive). Flow cytometric analysis confirmed the immature phenotype, with an expression of terminal deoxynucleotidyl transferase, combined with a loss of membrane immunoglobulins. The cytogenetic analysis performed on the ascites revealed a clonal evolution characterized by a t(8;22)(q24;q11) MYC+ translocation not previously detected in follicular lymphoma. Fluorescence in situ hybridization confirmed the double rearrangement of the BCL2 and MYC genes. Polymerase chain reactions and sequencing were used to study the clonal relationship between follicular lymphoma and the secondary tumors. The IGVH gene rearrangement revealed a unique clonal rearrangement involving an IGVH4-59 subset in all three specimens. CONCLUSION: These findings suggest a clonal relationship between the two types of lymphoma cells. Furthermore, they support the transformation of an acute follicular lymphoma into a composite lymphoma combining a high-grade B-cell lymphoma and a lymphoblastic neoplasm expressing terminal deoxynucleotidyl transferase. This case report highlights the possible transformation of follicular lymphoma into a highly aggressive and immature proliferation.

PHOX2B Immunostaining: A Simple and Helpful Tool for the Recognition of Ganglionic Cells and Diagnosis of Hirschsprung Disease.

Hirschsprung disease (HD) is a congenital disorder of the enteric nervous system that occurs in ∼1 in 5000 live births. It is characterized by the absence of ganglionic cells (GCs) in the distal intestine. The diagnosis relies on the thorough analysis of a rectal suction biopsy (RSB), which must show a complete absence of GCs after careful examination of at least 100 serial sections. Such a negative characteristic explains the difficulty of this diagnosis. Moreover, GCs may be immature in very young or preterm born children, making them hard to recognize. Therefore, ancillary techniques have been developed as diagnostic help, such as acetylcholinesterase histochemistry and calretinin immunostaining. These techniques reveal only indirect clues, focusing mainly on the changes in nerve fibers, but not on GCs themselves. As PHOX2B has been shown to be a very specific transcription factor in GCs and in progenitor enteric nerve cells, we have assessed (i) PHOX2B immunostaining in immature enteric ganglia and (ii) the use of PHOX2B immunostaining for the recognition of GCs on RSBs for suspicion of HD. We have observed PHOX2B expression in all GCs, both mature and immature, and its complete absence in Hirschsprung cases. We suggest that the use of PHOX2B immunostaining is of great help (i) in the recognition of GCs on RSBs regardless of their differentiation and therefore (ii) in the diagnosis of HD.

Clinical and histological differences between adults and children in new onset IgA nephropathy.

BACKGROUND: Previous reports suggest initial presentation of IgA nephropathy (IgAN) in children is different from adults. No systematic comparison of clinical, biological, and histological childhood- and adult-onset IgAN is currently available. METHODS: We compared pediatric and adult clinical and histological characteristics at IgAN diagnosis. Data on 211 consecutive patients from two different centers in Paris (82 children, 129 adults) were reviewed. Kidney biopsies were scored for Oxford classification and podocytopathic (P1) features. RESULTS: We report higher eGFR at diagnosis in children compared to adults (89.5 vs. 64 ml/min/1.73 m2; p = 0.0001) but no difference in proteinuria. Histological analysis of kidney biopsy found higher proportions of mesangial (M1) and endocapillary (E1) hypercellularity in children compared with adults (M1 [80.7% vs. 27.9%, p = 0.0001]; E1 [71.3% vs. 30%, p = 0.0001]). Focal glomerulosclerosis (S1), tubular atrophy/interstitial fibrosis ≥ 25% (T1), and P1 were more frequent in adults (S1 [81.5% vs. 61.3%, p = 0.0012], T1 [49.5% vs. 1.35%, p = 0.0001], P1 [33.8% vs. 16.4%, p = 0.008). Proteinuria associated with M1, E1, and C1 in children (M1, p = 0.0001; E1, p = 0.0005; C1, p = 0.0014) but S1, P1, and T1 in adults (S1, p = 0.0001; P1, p = 0.0001; T1, p = 0.001). After steroid treatment (41 children and 28 adults), proteinuria decreased in children (p < 0.001, follow-up 38 months) and adults (p < 0.001, follow-up 76.9 months), whereas eGFR remained stable in adults but increased significantly in children (90.6 to 110 ml/min/1.73m2). CONCLUSION: Proteinuria in children with IgAN is a marker of glomerular proliferative lesions whereas its presence in adults often reflects the presence of chronic lesions. This suggests the need for histological assessment.

Histological prognostic factors in children with Henoch-Schönlein purpura nephritis.

BACKGROUND: The management of IgA vasculitis with nephritis (IgAVN) remains controversial because of the difficulty to identify prognostic factors. This study reports the prognosis of children with IgAVN in relation to histological parameters. METHODS: All children with IgAVN diagnosed between 2000 and 2015 in three pediatric nephrology centers were included. The following histological parameters were analyzed: mesangial proliferation (MP), endocapillary proliferation (EP), crescents, active, or chronic tubular and interstitial lesions (TIa lesions/TIc lesions), and segmental glomerulosclerosis (GS). Clinical and biological data were collected at the time of renal biopsy. The primary endpoint was IgAVN remission defined as a proteinuria < 200 mg/l without renal failure. RESULTS: One hundred fifty-nine children were included with a median age of 7.6 years. Acute glomerular or TI lesions including MP, EP, crescents, and TIa lesions were observed, respectively, in 81%, 86%, 49%, and 21% of patients. Chronic glomerular lesions including GS and TIc lesions were observed in 6 and 7% of patients. Median initial proteinuria was 330 mg/mmol, albuminemia 32 g/l, and eGFR 110 ml/min/1.73 m2. One hundred twelve (70%) patients were in remission at the end of a median follow-up of 37.4 months. Chronic lesions were significantly associated with the absence of remission in multivariate analysis, whereas EP, crescents and TIa were not associated with a poor prognosis. CONCLUSIONS: Of children with IgAVN, 30% present a persistent renal disease at the end of a 3-year follow-up. Chronic histological lesions, but not EP or crescents, are associated with a bad prognosis and must be evaluated in IgAVN histological classification.

Remission of proteinuria in multidrug-resistant idiopathic nephrotic syndrome following immunoglobulin immunoadsorption.

AIM: Complete or partial resistance to prednisone and calcineurin inhibitors in children with idiopathic nephrotic syndrome often leads to end-stage renal disease. The aim of the study was to report the outcome of patients with multidrug-resistant nephrotic syndrome treated with an association of immunoglobulin immunoadsorption, intravenous immunoglobulins and B-cell depletion. METHODS: At treatment initiation, patients received ten sessions of immunoglobulin immunoadsorption and intravenous immunoglobulins in two weeks followed by one rituximab in case of remission. RESULTS: A remission of proteinuria was obtained in nine out of 14 patients at the end of the initial phase and in two additional patients after an extended period. The remission was stable in three patients and after additional IgIA and heavy immunosuppression in six. Two patients that initially responded relapsed after IgIA withdrawal and remained with an uncontrolled disease at last follow-up. Three patients did not respond to the treatment including two who were found to have a genetic podocytopathy. CONCLUSION: Patients with multidrug-resistant idiopathic nephrotic syndrome can be successfully led into remission by IgIA prior to reaching end-stage renal disease. However, IgIA does not suppress the need for heavy additional immunosuppression to control INS in most cases.

[Pulmonary glial heterotopia: Unique lesion in an infant with anencephalic twin]. / Hétérotopie gliale pulmonaire : une lésion exceptionnelle chez un nourrisson avec un jumeau anencéphale.

Pulmonary glial heterotopia is an extremely rare entity whose pathophysiology remains unclear. We report for the first time one case of pulmonary glial heterotopia occured in a one-month baby free from any malformation. She has the particularity of being born from monozygotic monochorionic twin pregnancy where her anencephalic exencephalic sister suffered a medical termination of pregnancy. She presented neonatal respiratory distress, which recurred one month later. Chest X-ray revealed bilateral cystic pulmonary lesions mainly located in the right lung. Given the suspicion of congenital cystic adenomatoid malformation (CCAM), she underwent an upper and a lower right lung lobectomy at four months old. The pathological study found a multi-cystic lesion consisted of well-differentiated and poorly cellular glial tissue sometimes lined by bronchic epithelium. There was no pathological evidence for a CCAM. The evolution was favorable after surgery with an infant who was well five months later. This is one of the very few cases where the disease did not lead to rapid death in utero or during the perinatal period. This suggests that effective management by surgery could be a decisive factor in the survival of these patients.

Immunosuppressive Treatment in Children With IgA Nephropathy and the Clinical Value of Podocytopathic Features.

INTRODUCTION: There is a need for treatment guidelines and prognostic factor identification in children with primary IgA nephropathy. We analyzed the causative effect of steroids and the applicability of the Oxford classification. METHODS: A total of 82 consecutive children (mean 10.6 years; median follow-up 3.3 years) were reviewed; 21 patients (25.6%) presented with acute kidney injury, and 6 (7.3%) with nephrotic syndrome. Renal biopsies were scored for Oxford classification and podocytopathic features in 2 groups: a group treated with steroid therapy (some in association with cyclophosphamide) and supportive care (renin angiotensin system blockade) and a group treated by supportive care alone. RESULTS: The 2 groups were not comparable because baseline clinical data were different. Estimated glomerular filtration rate (eGFR) in immunosupressive group significantly improved between M0 (at onset) and M6 (6 months after treatment) from 89.9 [61.2-114.5] to 110.5 [93.7-120] ml/min per 1.73 m2, P < 0.001. Proteinuria also significantly decreased from (1.6 [1-4.3] to 0.3 [0.2-0.7] g/g, P < 0.001). In the supportive care group, eGFR and proteinuria remained stable. Podocytopathic features were predictive of renal function decline by univariable (-4.9 ± 14.9 ml/min per 1.73 m2, P = 0.0079) and multivariable analysis and of poor renal prognosis to a combined event (renal function impairment more than 10% of the eGFR baseline or chronic kidney disease stage 3 at 6 months) in univariable analysis. MEST-C score failed to prove its prognostic value. CONCLUSION: Immunosuppressive treatment, especially steroid therapy, seems beneficial in children with glomerular inflammation and proliferation. The Oxford classification does not appear to be entirely appropriate in predicting long-term renal prognosis for children, whereas the characteristics of podocytopathy are strongly predictive of renal prognosis.

Activated ALK signals through the ERK-ETV5-RET pathway to drive neuroblastoma oncogenesis.

Activating mutations of the ALK receptor occur in a subset of neuroblastoma tumors. We previously demonstrated that Alk mutations cooperate with MYCN overexpression to induce neuroblastoma in mice and identified Ret as being strongly upregulated in MYCN/Alkmut tumors. By a genetic approach in vivo, we now document an oncogenic cooperation between activated Ret and MYCN overexpression in neuroblastoma formation. We show that MYCN/RetM919T tumors exhibit histological features and expression profiles close to MYCN/Alkmut tumors. We show that RET transcript levels decrease precedes RET protein levels decrease upon ALK inhibition in neuroblastoma cell lines. Etv5 was identified as a candidate transcription factor regulating Ret expression from murine MYCN/Alkmut tumor transcriptomic data. We demonstrate that ETV5 is regulated both at the protein and mRNA levels upon ALK activation or inhibition in neuroblastoma cell lines and that this regulation precedes RET modulation. We document that ALK activation induces ETV5 protein upregulation through stabilization in a MEK/ERK-dependent manner. We show that RNAi-mediated inhibition of ETV5 decreases RET expression. Reporter assays indicate that ETV5 is able to drive RET gene transcription. ChIP-seq analysis confirmed ETV5 binding on the RET promoter and identified an enhancer upstream of the promoter. Finally, we demonstrate that combining RET and ALK inhibitors reduces tumor growth more efficiently than each single agent in MYCN and AlkF1178L-driven murine neuroblastoma. Altogether, these results define the ERK-ETV5-RET pathway as a critical axis driving neuroblastoma oncogenesis downstream of activated ALK.

Ontogeny of human mucosal-associated invariant T cells and related T cell subsets.

Mucosal-associated invariant T (MAIT) cells are semi-invariant Vα7.2+ CD161highCD4- T cells that recognize microbial riboflavin precursor derivatives such as 5-OP-RU presented by MR1. Human MAIT cells are abundant in adult blood, but there are very few in cord blood. We longitudinally studied Vα7.2+ CD161high T cell and related subset levels in infancy and after cord blood transplantation. We show that Vα7.2+ and Vα7.2- CD161high T cells are generated early during gestation and likely share a common prenatal developmental program. Among cord blood Vα7.2+ CD161high T cells, the minority recognizing MR1:5-OP-RU display a TRAV/TRBV repertoire very similar to adult MAIT cells. Within a few weeks of life, only the MR1:5-OP-RU reactive Vα7.2+ CD161high T cells acquire a memory phenotype. Only these cells expand to form the adult MAIT pool, diluting out other Vα7.2+ CD161high and Vα7.2- CD161high populations, in a process requiring at least 6 years to reach adult levels. Thus, the high clonal size of adult MAIT cells is antigen-driven and likely due to the fine specificity of the TCRαß chains recognizing MR1-restricted microbial antigens.

Small bowel stenosis: a manifestation of chronic graft-versus-host disease in children?

Digestive graft-versus-host disease (GVHD) is a frequent complication after bone marrow transplantation, but small bowel obstruction is an extremely rare event. We present herein the first pediatric series of 4 cases of small bowel obstruction after bone marrow transplantation with detailed gross, histological data and their genetic status of the NOD2 gene. All patients had a history of severe acute GVHD treated by immunosuppressive agents and/or infliximab (in 3 cases). Acute or progressively worsening abdominal pain accompanied by small bowel occlusion occurred 5-16 months after graft, and computed tomographic scan revealed multiple small intestinal stenoses. Failure of intensive medical treatment led to surgical resection of affected loops. Stigmata of acute (apoptosis of crypts and satellitosis) and chronic GVHD features (submucosal fibrosis and serosae sclerolipomatosis), as well as extensive ulcerations, were observed in all ileal specimens. NOD2 mutation was found in only 1 patient. The follow-up showed successful outcome after surgery.

Expression of Disialoganglioside (GD2) in Neuroblastic Tumors: A Prognostic Value for Patients Treated With Anti-GD2 Immunotherapy.

Neuroblastoma, a malignant neoplasm of the sympathetic nervous system, is one of the most aggressive pediatric cancers. Patients with stage IV high-risk neuroblastoma receive an intensive multimodal therapy ending with an immunotherapy based on a chimeric monoclonal antibody ch14.18. Although the use of ch14.18 monoclonal antibody has significantly increased the survival rate of high-risk neuroblastoma patients, about 33% of these patients still relapse and die from their disease. Ch14.18 targets the disialoganglioside, GD2, expressed on neuroblastic tumor (NT) cells. To better understand the causes of tumor relapse following ch14.18 immunotherapy, we have analyzed the expression of GD2 in 152 tumor samples from patients with NTs using immunohistochemical stainings. We observed GD2 expression in 146 of 152 samples (96%); however, the proportion of GD2-positive cells varied among samples. Interestingly, low percentage of GD2-positive cells before immunotherapy was associated with relapse in patients receiving ch14.18 immunotherapy. In addition, we demonstrated in vitro that the sensitivity of neuroblastoma cell lines to natural killer-mediated lysis was dependent on the proportion of GD2-positive cells, in the presence of ch14.18 antibody. In conclusion, our results indicate that the proportion of tumor cells expressing GD2 in NTs should be taken in consideration, as a prognostic marker, for high-risk neuroblastoma patients receiving anti-GD2 immunotherapy.

Whole-Exome Sequencing of Cell-Free DNA Reveals Temporo-spatial Heterogeneity and Identifies Treatment-Resistant Clones in Neuroblastoma.

Purpose: Neuroblastoma displays important clinical and genetic heterogeneity, with emergence of new mutations at tumor progression.Experimental Design: To study clonal evolution during treatment and follow-up, an innovative method based on circulating cell-free DNA (cfDNA) analysis by whole-exome sequencing (WES) paired with target sequencing was realized in sequential liquid biopsy samples of 19 neuroblastoma patients.Results: WES of the primary tumor and cfDNA at diagnosis showed overlap of single-nucleotide variants (SNV) and copy number alterations, with 41% and 93% of all detected alterations common to the primary neuroblastoma and cfDNA. CfDNA WES at a second time point indicated a mean of 22 new SNVs for patients with progressive disease. Relapse-specific alterations included genes of the MAPK pathway and targeted the protein kinase A signaling pathway. Deep coverage target sequencing of intermediate time points during treatment and follow-up identified distinct subclones. For 17 seemingly relapse-specific SNVs detected by cfDNA WES at relapse but not tumor or cfDNA WES at diagnosis, deep coverage target sequencing detected these alterations in minor subclones, with relapse-emerging SNVs targeting genes of neuritogenesis and cell cycle. Furthermore a persisting, resistant clone with concomitant disappearance of other clones was identified by a mutation in the ubiquitin protein ligase HERC2Conclusions: Modelization of mutated allele fractions in cfDNA indicated distinct patterns of clonal evolution, with either a minor, treatment-resistant clone expanding to a major clone at relapse, or minor clones collaborating toward tumor progression. Identification of treatment-resistant clones will enable development of more efficient treatment strategies. Clin Cancer Res; 24(4); 939-49. ©2017 AACR.