Whole-body magnetic resonance imaging for staging Langerhans cell histiocytosis in children and young adults.

INTRODUCTION: Radiographic skeletal survey (R-SS) is the standard imaging technique for the initial staging of Langerhans cell histiocytosis (LCH). Whole-body magnetic resonance imaging (WB-MRI) has been proposed as an effective, radiation-free alternative. METHODS: We prospectively assessed patients with LCH followed at three tertiary centers in Italy and Austria. Two national study protocols were independently designed, and data were then pooled to increase the power of their findings. R-SS and WB-MRI were performed at diagnosis and repeated at the follow-up to confirm the nature of the identified lesions and to study their evolution. RESULTS: Data from 67 patients were analyzed (52 from Italy and 15 from Austria). Compared to R-SS, WB-MRI identified 29 additional skeletal lesions in 14 patients (including two false-positive lesions). Two skeletal lesions were detected at R-SS and missed at WB-MRI (false negative). Per-lesion sensitivity rates were 78.6% (95% CI: 71.0-85.9) for R-SS and 98.4% (95% CI: 94.4-99.8) for WB-MRI, respectively. Based on WB-MRI findings, six patients would have been upstaged to a higher risk class than staging with R-SS. CONCLUSIONS: WB-MRI had a significantly higher detection rate for skeletal lesions compared to R-SS. Clinical and radiology expertise is required to avoid upstaging and overtreatment.

[Updated AWMF Guideline on the Diagnosis and Treatment of Langerhans cell Histiocytosis in Children and Adolescents]. / Aktualisierte AWMF Leitlinie zur Diagnostik und Therapie der Langerhanszell Histiozytose (LCH) im Kindes- und Jugendalter.

Langerhans cell Histiocytosis is a rare neoplastic disease, which occurs mainly in children and adolescents. The disease may affect any organ, and therefore, the clinical symptoms vary widely. Some patients have a spontaneous remission of the disease, whereas others experience a rapid and potentially lethal clinical course. The therapeutic approach depends on the extent of the disease, and reaches from a watch-and-wait strategy to chemotherapy with the standard drugs vinblastine and prednisone. The identification of mutations in the MAPK-pathway resulted in growing interest in targeted therapy using compounds such as the BRAF inhibitors. Chronic relapses and permanent sequelae are important problems of LCH and are the focus of current research.

MRI Characteristics of Pediatric Renal Tumors: A SIOP-RTSG Radiology Panel Delphi Study.

BACKGROUND: The SIOP-Renal Tumor Study Group (RTSG) does not advocate invasive procedures to determine histology before the start of therapy. This may induce misdiagnosis-based treatment initiation, but only for a relatively small percentage of approximately 10% of non-Wilms tumors (non-WTs). MRI could be useful for reducing misdiagnosis, but there is no global consensus on differentiating characteristics. PURPOSE: To identify MRI characteristics that may be used for discrimination of newly diagnosed pediatric renal tumors. STUDY TYPE: Consensus process using a Delphi method. POPULATION: Not applicable. FIELD STRENGTH/SEQUENCE: Abdominal MRI including T1- and T2-weighted imaging, contrast-enhanced MRI, and diffusion-weighted imaging at 1.5 or 3 T. ASSESSMENT: Twenty-three radiologists from the SIOP-RTSG radiology panel with ≥5 years of experience in MRI of pediatric renal tumors and/or who had assessed ≥50 MRI scans of pediatric renal tumors in the past 5 years identified potentially discriminatory characteristics in the first questionnaire. These characteristics were scored in the subsequent second round, consisting of 5-point Likert scales, ranking- and multiple choice questions. STATISTICAL TESTS: The cut-off value for consensus and agreement among the majority was ≥75% and ≥60%, respectively, with a median of ≥4 on the Likert scale. RESULTS: Consensus on specific characteristics mainly concerned the discrimination between WTs and non-WTs, and WTs and nephrogenic rest(s) (NR)/nephroblastomatosis. The presence of bilateral lesions (75.0%) and NR/nephroblastomatosis (65.0%) were MRI characteristics indicated as specific for the diagnosis of a WT, and 91.3% of the participants agreed that MRI is useful to distinguish NR/nephroblastomatosis from WT. Furthermore, all participants agreed that age influenced their prediction in the discrimination of pediatric renal tumors. DATA CONCLUSION: Although the discrimination of pediatric renal tumors based on MRI remains challenging, this study identified some specific characteristics for tumor subtypes, based on the shared opinion of experts. These results may guide future validation studies and innovative efforts. LEVEL OF EVIDENCE: 3 Technical Efficacy Stage: 3.

Langerhans Cell Histiocytosis of the Orbit: Spectrum of Clinical and Imaging Findings.

OBJECTIVE: To evaluate the clinical and imaging characteristics of orbital lesions of pediatric Langerhans cell histiocytosis (LCH). STUDY DESIGN: A retrospective analysis of clinical data and central review of magnetic resonance imaging scans in patients with LCH, enrolled into one of the consecutive international trials LCH I-III, or submitted for a second opinion between 1994 and 2015. RESULTS: Data from 31 children (34 involved orbits) were analyzed. Orbital LCH was the only disease manifestation in 15, part of a multifocal skeletal in 5, or a multisystem LCH in 11 patients. Orbital LCH was part of the initial disease presentation in 23 or developed at relapse in 8 cases. Orbital involvement was unilateral in 28 and bilateral in 3 patients (34 affected orbits). Proptosis was present in 9 patients. Frontal and zygomatic bone were most commonly affected. All orbital lesions were extraconal. Associated extraorbital imaging findings were dural tail sign in 19, neurodegeneration in 8, and hypothalamic-pituitary mass in 3 patients. Sixteen patients (52%) had at least 1 documented disease relapse. Permanent consequences were prominent proptosis in 1, diabetes insipidus in 8, growth hormone deficiency in 2, radiologic neurodegeneration in 8, and clinical neurodegeneration in 3 patients. CONCLUSIONS: Predominantly unilateral orbital LCH can be the only disease manifestation or part of a disseminated disease. Orbital lesions in LCH are exclusively extraconal, typically located at the roof and the lateral wall of the orbit. The optimal treatment approach of unifocal LCH of the orbit remains controversial and warrants a prospective evaluation.

Unexplored Nucleotide Binding Modes for the ABC Exporter MsbA.

The ATP-binding cassette (ABC) transporter MsbA is an ATP-driven lipid-A flippase. It belongs to the ABC protein superfamily whose members are characterized by conserved motifs in their nucleotide binding domains (NBDs), which are responsible for ATP hydrolysis. Recently, it was found that MsbA could catalyze a reverse adenylate kinase (rAK)-like reaction in addition to ATP hydrolysis. Both reactions are connected and mediated by the same conserved NBD domains. Here, the structural foundations underlying the nucleotide binding to MsbA were therefore explored using a concerted approach based on conventional- and DNP-enhanced solid-state NMR, pulsed-EPR, and MD simulations. MsbA reconstituted into lipid bilayers was trapped in various catalytic states corresponding to intermediates of the coupled ATPase-rAK mechanism. The analysis of nucleotide-binding dependent chemical shift changes, and the detection of through-space contacts between bound nucleotides and MsbA within these states provides evidence for an additional nucleotide-binding site in close proximity to the Q-loop and the His-Switch. By replacing Mg2+ with Mn2+ and employing pulsed EPR spectroscopy, evidence is provided that this newly found nucleotide binding site does not interfere with the coordination of the required metal ion. Molecular dynamic (MD) simulations of nucleotide and metal binding required for the coupled ATPase-rAK mechanism have been used to corroborate these experimental findings and provide additional insight into nucleotide location, orientation, and possible binding modes.

Thoracic Actinomycosis With Infiltration of the Spine: An Oncological Pitfall.

Thoracic actinomycosis with involvement of the vertebral column and chest wall is rare in children and may resemble malignant tumors. A 12-year-old girl was admitted to our clinic having B-symptoms, cachexia, and painful scoliosis (Karnofsky index 20%). Imaging showed a large thoracic left-sided paravertebral tumor with infiltration of the vertebrae, destruction of the chest wall and multiple intrapulmonary nodules. Initially, Ewing sarcoma was suspected and chemotherapy started without previous biopsies. Definite diagnosis of actinomycosis was established later upon histopathologic examination and successfully treated by ß-lactam antibiotics. Collectively, this case illustrates that actinomycosis can be an oncological pitfall and possible differential diagnosis.

Outcome of two patients with bilateral nephroblastomatosis/Wilms tumour treated with an add-on 13-cis retinoic acid therapy - Case report.

Although the fate of nephrogenic rests varies, they are known to be precursors of Wilms tumour. Thus, nephrogenic rests require adequate treatment to prevent malignant transformation. We added 13-cis retinoic acid to the standard chemotherapy with vincristine and actinomycin-D in two patients with bilateral nephrogenic rests/nephroblastomatosis. Patient 1 also had a history of Wilms tumour. 46 (patient 1) and 81 (patient 2) months after end of treatment, both patients show stable conditions with no signs of relapse or progressive disease. Our observation supports further investigation of retinoic acid in patients with nephrogenic rests and nephroblastomatosis.

NF-κB1 Haploinsufficiency Causing Immunodeficiency and EBV-Driven Lymphoproliferation.

PURPOSE: NF-κB signaling is critically important for regulation of both innate and adaptive immune responses. While activation of NF-κB has been implicated in malignancies such as leukemia and lymphoma, loss-of-function mutations affecting different NF-κB pathway components have been shown to cause primary immunodeficiency disorders. Recently, haploinsufficiency of NF-κB1 has been described in three families with common variable immunodeficiency (CVID). METHODS AND RESULTS: We studied a patient with recurrent respiratory infections and bacterial parapharyngeal abscess. Immunological investigations revealed normal total B- cell numbers, but hypogammaglobulinemia, decreased frequencies of class-switched B cells and impaired T-cell proliferation. Targeted next-generation sequencing using a custom-designed panel comprising all known PID genes (IUIS 2014 classification) and novel candidate genes identified a novel heterozygous frameshift mutation in the NFKB1 gene leading to a premature stop codon (c.491delG; p.G165A*31). We could show that the mutation leads to reduced phosphorylation of p105 upon stimulation, resulting in decreased protein levels of p50. The further disease course was mainly characterized by two episodes of severe EBV-associated lymphoproliferative disease responsive to rituximab treatment. Due to disease severity, the patient is considered for allogeneic hematopoietic stem cell transplantation. Interestingly, the father carries the same heterozygous NFKB1 mutation and also shows decreased frequencies of memory B cells but has a much milder clinical phenotype, in line with a considerable phenotypic disease heterogeneity. CONCLUSIONS: Deficiency of NF-κB1 leads to immunodeficiency with a wider phenotypic spectrum of disease manifestation than previously appreciated, including EBV lymphoproliferative diseases as a hitherto unrecognized feature of the disease.

Radiological features of thymic langerhans cell histiocytosis.

TI was reported in 18/1,264 (1.4%) LCH patients. All nine patients with TI at initial LCH presentation were below 2 years of age and had multisystem LCH (9/242, 4%). Images (sonography, CT, MRI) for central review were available in 15 cases. Characteristic findings of TI were thymus enlargement (67%), few to many cysts (80%), and few to many calcifications (100%). Sonographic and MRI findings were in excellent agreement. We recommend adding sonography of the thymus to the standard for initial clinical evaluation of LCH patients below the age of 2 years.

Clinical and immunological correction of DOCK8 deficiency by allogeneic hematopoietic stem cell transplantation following a reduced toxicity conditioning regimen.

Dedicator of cytokinesis 8 protein (DOCK8) deficiency is a combined immunodeficiency disorder characterized by an expanding clinical picture with typical features of recurrent respiratory or gastrointestinal tract infections, atopic eczema, food allergies, chronic viral infections of the skin, and blood eosinophilia often accompanied by elevated serum IgE levels. The only definitive treatment option is allogeneic hematopoietic stem cell transplantation (HSCT). We report a patient with early severe manifestation of DOCK8 deficiency, who underwent unrelated allogeneic HSCT at the age of 3 years following a reduced toxicity conditioning regimen. The transplant course was complicated by pulmonary aspergilloma pretransplantation, adenovirus (ADV) reactivation, and cytomegalovirus (CMV) pneumonitis 4 weeks after transplantation. With antifungal and antiviral treatment the patient recovered. Seven months after transplantation the patient is in excellent clinical condition. Eczematous rash, chronic viral skin infections, and food allergies have subsided, associated with normalization of IgE levels and absolute numbers of eosinophils. Chimerism analysis shows stable full donor chimerism. DOCK8 deficiency can be successfully cured by allogeneic HSCT. This treatment option should be considered early after diagnosis, as opportunistic infections and malignancies that occur more frequently during the natural course of the disease are associated with higher morbidity and mortality.

Occurrence of autoimmune pancreatitis after chronic immune thrombocytopenia in a Caucasian adolescent.

Autoimmune pancreatitis is a rare, distinct and increasingly recognized form of chronic inflammatory pancreatic disease secondary to an underlying autoimmune mechanism. We report on a 14-year-old boy who developed autoimmune pancreatitis, while he was under treatment with eltrombopag for chronic immune thrombocytopenia. Therapy with corticosteroids resulted in complete remission of both. This is the first report on the co-occurrence of autoimmune pancreatitis and chronic immune thrombocytopenia in childhood, and clinicians should be aware of this rare association, because early diagnosis and therapy of autoimmune pancreatitis may prevent severe complications.

Diagnosis and management of acute appendicitis in 21 pediatric hematology and oncology patients at a tertiary care cancer center.

Acute appendicitis is a rare gastrointestinal complication of anti-cancer chemotherapy and hematopoietic stem cell transplantation. Among a cohort of 2341 hemato-oncologic patients at a pediatric tertiary care cancer center, we identified 21 patients (0.9%) with 23 episodes of acute appendicitis, based on pathological imaging of the appendix and clinical findings. Median age at diagnosis was 10.21 years. Types of underlying disease included acute leukemias (n = 15), solid tumors (n = 4), and aplastic anemia (n = 2). Clinical symptoms seen in > 1 case were recorded for all 23 episodes as follows: abdominal pain, n = 22; abdominal tenderness, n = 4; fever, n = 7; nausea, n = 2; emesis; n = 2; diarrhea, n = 5; and constipation, n = 2. Median leukocyte count at diagnosis was 0.5 × 109/L, with a median of 0.1 × 109/L for the absolute neutrophil count (ANC). All patients received broad-spectrum antibiotics and 18/23 (78%) patients underwent uneventful appendectomy after a median of 5 days and with a median ANC of 0.7 × 109/L. Median duration until continuation of chemotherapy was 17 days for the 20 cases of appendicitis occurring during the patients' disease course. Overall, 5/21 (19%) patients died including one related to the appendicitis itself which progressed to a typhlitis and was due to a fungal infection. The other fatalities were transplant- (n = 2) and leukemia-related (n = 2). Acute appendicitis is a rare and usually not life-threatening event in pediatric hemato-oncologic patients, which, if managed by prompt administration of broad-spectrum antibiotics (and antimycotics), can be safely followed by an elective (delayed) appendectomy, even before complete recovery of the neutrophils is achieved.

Coupled ATPase-adenylate kinase activity in ABC transporters.

ATP-binding cassette (ABC) transporters, a superfamily of integral membrane proteins, catalyse the translocation of substrates across the cellular membrane by ATP hydrolysis. Here we demonstrate by nucleotide turnover and binding studies based on 31P solid-state NMR spectroscopy that the ABC exporter and lipid A flippase MsbA can couple ATP hydrolysis to an adenylate kinase activity, where ADP is converted into AMP and ATP. Single-point mutations reveal that both ATPase and adenylate kinase mechanisms are associated with the same conserved motifs of the nucleotide-binding domain. Based on these results, we propose a model for the coupled ATPase-adenylate kinase mechanism, involving the canonical and an additional nucleotide-binding site. We extend these findings to other prokaryotic ABC exporters, namely LmrA and TmrAB, suggesting that the coupled activities are a general feature of ABC exporters.