Hallmarks of transcriptional intratumour heterogeneity across a thousand tumours.

Each tumour contains diverse cellular states that underlie intratumour heterogeneity (ITH), a central challenge of cancer therapeutics1. Dozens of recent studies have begun to describe ITH by single-cell RNA sequencing, but each study typically profiled only a small number of tumours and provided a narrow view of transcriptional ITH2. Here we curate, annotate and integrate the data from 77 different studies to reveal the patterns of transcriptional ITH across 1,163 tumour samples covering 24 tumour types. Among the malignant cells, we identify 41 consensus meta-programs, each consisting of dozens of genes that are coordinately upregulated in subpopulations of cells within many tumours. The meta-programs cover diverse cellular processes including both generic (for example, cell cycle and stress) and lineage-specific patterns that we map into 11 hallmarks of transcriptional ITH. Most meta-programs of carcinoma cells are similar to those identified in non-malignant epithelial cells, suggesting that a large fraction of malignant ITH programs are variable even before oncogenesis, reflecting the biology of their cell of origin. We further extended the meta-program analysis to six common non-malignant cell types and utilize these to map cell-cell interactions within the tumour microenvironment. In summary, we have assembled a comprehensive pan-cancer single-cell RNA-sequencing dataset, which is available through the Curated Cancer Cell Atlas website, and leveraged this dataset to carry out a systematic characterization of transcriptional ITH.

Risk factors for haemodynamic compromise in multisystem inflammatory syndrome in children: a multicentre retrospective study.

OBJECTIVES: To identify predictors of a severe clinical course of multisystem inflammatory syndrome in children (MIS-C), as defined by the need for inotropic support. METHODS: This retrospective study included patients diagnosed with MIS-C (according to the CDC definition) in nine Israeli and one US medical centre between July 2020 and March 2021. Univariate and multivariate regression models assessed odds ratio (OR) of demographic, clinical, laboratory and imaging variables during admission and hospitalization for severe disease. RESULTS: Of 100 patients, 61 (61%) were male; mean age 9.65 (4.48) years. Sixty-five patients were hypotensive, 44 required inotropic support. Eleven patients with MIS-C fulfilled Kawasaki disease diagnostic criteria; 87 had gastrointestinal symptoms on admission. Echocardiographic evaluation showed 10 patients with acute coronary ectasia or aneurysm, and 37 with left ventricular dysfunction. In a univariate model, left ventricular dysfunction was associated with severe disease [OR 4.178 (95% CI 1.760, 9.917)], while conjunctivitis [OR 0.403 (95% CI 0.173, 0.938)] and mucosal changes [OR 0.333 (95% CI 0.119, 0.931)] at admission were protective. Laboratory markers for a severe disease course were low values of haemoglobin, platelets, albumin and potassium; and high leukocytes, neutrophils, troponin and brain natriuretic peptide. In multivariate analysis, central nervous system involvement and fever >39.5°C were associated with severe disease. Mucosal involvement showed 6.2-fold lower risk for severe disease. Low haemoglobin and platelet count, and elevated C-reactive protein and troponin levels were identified as risk factors for severe disease. CONCLUSION: Key clinical and laboratory parameters of MIS-C were identified as risk factors for severe disease, predominantly during the disease course and not at the time of admission; and may prompt close monitoring, and earlier, more aggressive treatment decisions. Patients presenting with a Kawasaki-like phenotype were less likely to require inotropic support.

Performance of 2019 EULAR/ACR classification criteria for systemic lupus erythematosus in a paediatric population-a multicentre study.

OBJECTIVES: The European League Against Rheumatism and American College of Rheumatology 2019 (EULAR/ACR-19) criteria for the diagnosis of SLE were recently published, with the stated goal of maintaining the level of sensitivity and raising the level of specificity for classification of SLE in adults. The aim of this study is to examine their application to juvenile SLE (jSLE) patients. METHODS: In this multicentre study the charts of jSLE patients from three tertiary medical centres were reviewed and compared with patients with non-jSLE diagnosis. Paediatric rheumatologists, blinded to the original diagnosis, reviewed and diagnosed all cases. Paediatric patients' clinical and laboratory data were retrospectively extracted and then examined with regard to how they met the new and old criteria. RESULTS: Included were 225 patients (112 jSLE, 113 non-SLE). When applied to juvenile SLE classification, the sensitivity of the new EULAR/ACR-19 criteria was 0.96 (95% CI: 0.9, 0.99) and the specificity was 0.89 (95% CI: 0.82, 0.94). These were comparable to the SLICC criteria. The sensitivity of the EULAR/ACR-19 criteria improves over time and was 0.83 12 months following disease onset, reaching 0.96 after longer than 24 months. CONCLUSION: Among a cohort of jSLE patients, sensitivity of the new EULAR/ACR-19 criteria was found to be high and specificity may have improved slightly compared with the SLICC-12 criteria. We support the use of the new classification criteria for paediatric patients in future jSLE studies, but it should be noted that its specificity is lower than for adults.

Safety and efficacy of intravenous Colchicine in children with Familial Mediterranean Fever.

Familial Mediterranean Fever (FMF), the most common monogenic inflammatory disease, is mainly treated by oral Colchicine. However, 5% of patients are considered non-responders and, therefore, candidates for biologic therapy. Intravenous (IV) Colchicine treatment has been shown to be effective and safe in adult patients. The objective of this study was to evaluate the safety of IV Colchicine for pediatric FMF patients in our hospital, refractory to oral Colchicine, by reviewing their medical records. Inclusion criteria were all patients with FMF who commenced treatment with IV Colchicine before the age of 18 years, and received at least 6 months of IV therapy. The patients completed questionnaires to assess the efficacy of the treatment. Between 2004 and 2017, 7 pediatric FMF patients receiving maximal oral Colchicine doses and deemed non-responders were treated with weekly IV Colchicine, including 38 cumulative patient years of follow-up data (a full blood count, renal and liver function tests). All patients were homozygous for the M694V genotype. Long-term follow-up showed normal laboratory results with no Colchicine-related hospital admissions or toxicity. Global health assessment and the number of disease-free days have significantly improved (P < 0.05). Prolonged IV Colchicine use is described in pediatric FMF patients for the first time, with an excellent safety profile in our population, and decrease in intensity and frequency of attacks. In the biological era, IV Colchicine, although not leading to complete remission, may be considered a second-line option in countries where anti-interleukin 1 blockers are not available, or as a third-line option in case of failure to respond to biologics.

Musculoskeletal Manifestations as Presenting Symptoms of Inflammatory Bowel Disease in Children and Adolescents.

A comparison of 23 children with inflammatory bowel disease presenting with musculoskeletal symptoms and 46 children with arthritis of other causes yielded significantly higher rates in the inflammatory bowel disease group of sacroiliitis, arthralgia, additive and recurrent arthritis, microcytic anemia, elevated inflammatory markers, and hypoalbuminemia. Clinical awareness of these findings could expedite diagnosis and treatment.

Discovery of a Novel Missense Variant in NLRP3 Causing Atypical Cryopyrin-Associated Periodic Syndromes With Hearing Loss as the Primary Presentation, Responsive to Anti-Interleukin-1 Therapy.

OBJECTIVE: Cryopyrin-associated periodic syndromes (CAPS), also known as NLRP3-associated autoinflammatory diseases, are a spectrum of rare autoinflammatory diseases caused by gain-of-function variants in the NLRP3 gene, resulting in inflammasome hyperactivation and dysregulated release of interleukin-1ß (IL-1ß). Many patients with CAPS develop progressive sensorineural hearing loss (SNHL) because of cochlear autoinflammation, which may be the sole manifestation in rare cases. This study was undertaken to establish the suspected diagnosis of CAPS in a family presenting with autosomal-dominant progressive/acute SNHL and a novel missense variant in the NLRP3 gene of unknown significance (NM_001079821.3:c.1784G>A p.Ser595Asn). METHODS: We conducted an ex vivo functional assessment of the NLRP3 inflammasome in heterozygous individuals (n = 10) and healthy family members (n = 5). RESULTS: The assay revealed hyperactivation of the inflammasome among heterozygous individuals, supporting the hypothesis that this missense variant is a pathogenic gain-of-function variant. Administration of IL-1 receptor antagonist resulted in a substantial clinical improvement among pediatric patients, who exhibited near resolution of hearing impairment within 1 to 3 months of treatment. CONCLUSION: Our findings highlight the crucial role of early diagnosis and treatment with an anti-IL-1 agent in reversing cochlear damage. Furthermore, our results suggest that high- and ultrahigh-frequency ranges need to be included in the auditory assessment to enable early detection of subclinical SNHL. Finally, incorporating functional inflammasome assessment as part of the clinical evaluation could establish the diagnosis in inconclusive cases.

An "On Demand" canakinumab regimen for treating children with Colchicine-Resistant familial Mediterranean fever - A multicentre study.

OBJECTIVES: Canakinumab, a human monoclonal antibody targeted at interleukin-1 beta, has demonstrated safety and efficacy in preventing familial Mediterranean fever (FMF) attacks among individuals with colchicine-resistant (crFMF). The manufacturer orders prescribe monthly subcutaneous injections. However, a subset of our patients is treated with an "canakinumab on demand " (COD) strategy, with wider intervals between drug administrations. Therefore, we aimed to compare disease activity and drug safety between COD and "canakinumab fixed frequency" (CFF) policies. METHODS: This retrospective study collected data from three Israeli paediatric rheumatology centres, of children with crFMF who were treated with canakinumab. Epidemiological and clinical parameters, cumulative drug dosages, and adverse events were compared between children treated by both policies. RESULTS: Twenty-five (49 %) children were treated according to COD policy and 26 according to CFF policy. Demographic parameters and most of the disease features did not differ significantly between the groups. Both groups showed significant reduction in attacks after canakinumab introduction. The median number (interquartile range) of attacks per month did not differ significantly between the COD and CFF groups (0.33 (0.08, 0.58) and 0.13 (0, 0.5), respectively, p = 0.485 (even though, per definition, COD patients presumably had an attack before receiving the second canakinumab dose). The mean monthly dose was lower for the COD than the CFF group (1.13 ± 1.13 vs. 3.16 ± 1.46 mg/kg, p < 0.001). Adverse events were similar between the groups. CONCLUSION: For individuals with crFMF, COD compared to CFF policy can achieve similar efficacy and safety, with a lower accumulated canakinumab dose, rendering it less immunosuppressive and less expensive.

Pulse corticosteroid therapy for alopecia areata in children: a retrospective study.

BACKGROUND/OBJECTIVE: Alopecia areata may occur at any age, though usually before the age of 20 years. Treatment often consists of systemic steroids administered as high-dose bolus infusions. This study sought to investigate the effectiveness and side effects of intravenous high-dose pulse corticosteroids in children with alopecia areata and to identify prognostic factors for successful treatment. METHODS: Patients treated with pulse corticosteroids for alopecia areata in 2001-2008 at the day care unit of a tertiary pediatric medical center were identified by computerized file search and clinical treatment and outcome data were collected. RESULTS: The sample included 24 children (16 female, 8 male) with a mean age of 8.5 ± 4.6 years at diagnosis; 8 (33%) had multifocal disease,10 (42%) multifocal disease with ophiasis, 4 (17%) alopecia totalis and 2 (8%) alopecia universalis. Nail involvement was noted in 9 patients (38%). Mean duration of disease was 22 ± 27 months. Patients were treated with 8 mg/kg body weight intravenous methylprednisolone on 3 consecutive days at 1-month intervals. After a mean of 5.65 ± 1.95 courses, 9 patients (38%) had a complete response, 7 (29%) a partial response and 8 (33%) no response. Of the 16 responders, 13 (81%) relapsed at 9.5 ± 12 months after the last course; 3 patients had side effects, none of which were severe. Three positive prognostic factors were identified: short disease duration (≤6 months), younger age at disease onset (<10 years) and multifocal disease (as opposed to severe, diffuse variants). CONCLUSIONS: Careful patient selection is necessary to achieve maximal benefit from pulse corticosteroid treatment for alopecia areata in children.

Adherence to colchicine prophylaxis among patients with familial Mediterranean fever treated with interleukin-1 inhibitors.

OBJECTIVE: Interleukin-1 (IL-1) inhibitors are approved for treating familial Mediterranean fever (FMF) that is resistant to colchicine. However, continued concomitant treatment with colchicine is imperative, as it is the only drug proven to prevent secondary amyloidosis. We aimed to compare the adherence to colchicine between patients with colchicine-resistant FMF (crFMF) who were treated with IL-1 inhibitors and patients with colchicine-sensitive FMF (csFMF) who were treated only with colchicine. METHODS: The databases of Maccabi Health Services, a 2.6-million-member state-mandated health provider in Israel were searched for patients with FMF diagnosis. The medication possession ratio (MPR), calculated from the day of the first colchicine purchase (index date) until the last colchicine purchase was the main outcome measure. Patients with crFMF were matched in a 1:4 ratio to patients with csFMF. RESULTS: The final cohort included 4526 patients. Of them, 108 (2.4%) were with crFMF, and were matched to 432 with csFMF. The total mean MPR in each of the matched groups was similar (78.9 ± 41.4 and 82.5 ± 80.6, respectively, P = 0.5). Statistically significant differences in MPR were not found between the groups according to age or duration of colchicine use. However, adherence to colchicine was insufficient (MPR<80%) among more than 50% of the patients in both groups. CONCLUSION: In contrast to initial concerns, adherence to colchicine was similar between patients with crFMF and csFMF. However, in both groups, adherence to colchicine was poor. Education of both caregivers and patients is essential to increase adherence.

Extreme Periodic Fever, Aphthous Stomatitis, Pharyngitis, Adenitis (PFAPA): a discrete group of patients.

OBJECTIVE: Periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome is the most common periodic fever syndrome in children; by definition, episodes occur every 2 to 8 weeks. However, in a subset of our patients, we noticed a higher frequency of attacks, of less than 2 weeks, which we refer to as extreme PFAPA (ePFAPA). This group consisted of patients who were extreme upon presentation of PFAPA, and those who became extreme after initiation of abortive corticosteroid treatment. We aimed to characterize demographic and clinical features of ePFAPA, including the two groups, and to compare them to patients with non-extreme PFAPA (nPFAPA). STUDY DESIGN: The medical records of 365 patients with PFAPA who attended Schneider Children's Medical Center of Israel from March 2014 to April 2021 were reviewed. Patients with concomitant familial Mediterranean fever were excluded. Characteristics of the ePFAPA (including subgroups) and nPFAPA groups were compared using Wilcoxon rank sum, Pearson's chi-squared, and Fisher's exact tests. RESULTS: Forty-seven patients (12.9%) were identified as having ePFAPA. Among patients with ePFAPA, compared to patients with nPFAPA, the median (interquartile range) age at disease onset was earlier: 1.5 years (0.7-2.5) vs. 2.5 years (1.5-4.0), P < 0.001; and diagnosis was younger: 2.6 years (2.0-3.6) vs. 4.5 years (3.0-6.2), P < 0.001. A higher proportion of patients with ePFAPA than nPFAPA were treated with colchicine prophylaxis (53% vs. 19%, P < 0.001), but symptoms and signs during flares did not differ significantly between these groups. Demographic and clinical characteristics were similar between patients with ePFAPA from presentation of PFAPA (22, 47% of those with ePFAPA) and ePFAPA from after corticosteroid treatment. CONCLUSION: About half the patients categorized with ePFAPA syndrome already had extreme features upon presentation. Patients with ePFAPA compared to nPFAPA presented and were diagnosed at an earlier age.

Spectrum of Response to Platinum and PARP Inhibitors in Germline BRCA-Associated Pancreatic Cancer in the Clinical and Preclinical Setting.

Germline BRCA-associated pancreatic ductal adenocarcinoma (glBRCA PDAC) tumors are susceptible to platinum and PARP inhibition. The clinical outcomes of 125 patients with glBRCA PDAC were stratified based on the spectrum of response to platinum/PARP inhibition: (i) refractory [overall survival (OS) <6 months], (ii) durable response followed by acquired resistance (OS <36 months), and (iii) long-term responders (OS >36 months). Patient-derived xenografts (PDX) were generated from 25 patients with glBRCA PDAC at different clinical time points. Response to platinum/PARP inhibition in vivo and ex vivo culture (EVOC) correlated with clinical response. We deciphered the mechanisms of resistance in glBRCA PDAC and identified homologous recombination (HR) proficiency and secondary mutations restoring partial functionality as the most dominant resistant mechanism. Yet, a subset of HR-deficient (HRD) patients demonstrated clinical resistance. Their tumors displayed basal-like molecular subtype and were more aneuploid. Tumor mutational burden was high in HRD PDAC and significantly higher in tumors with secondary mutations. Anti-PD-1 attenuated tumor growth in a novel humanized glBRCA PDAC PDX model. This work demonstrates the utility of preclinical models, including EVOC, to predict the response of glBRCA PDAC to treatment, which has the potential to inform time-sensitive medical decisions. SIGNIFICANCE: glBRCA PDAC has a favorable response to platinum/PARP inhibition. However, most patients develop resistance. Additional treatment options for this unique subpopulation are needed. We generated model systems in PDXs and an ex vivo system (EVOC) that faithfully recapitulate these specific clinical scenarios as a platform to investigate the mechanisms of resistance for further drug development. This article is highlighted in the In This Issue feature, p. 1749.

The efficacy and safety of intra-articular injection of triamcinolone acetonide versus triamcinolone hexacetonide for treatment of juvenile idiopathic arthritis.

OBJECTIVES: Juvenile idiopathic arthritis (JIA) is the most common childhood rheumatic disease. Intra-articular corticosteroids joint injection (IAJI), with triamcinolone hexacetonide (TH) or triamcinolone acetonide (TA), is an effective additional treatment for oligo and polyarticular JIA. Previous studies have shown the benefits of TH over TA; however, TA is still used in many pediatric rheumatology centers. Our unit has experience with both regimens, and therefore we aimed to compare the efficacy and safety of TA versus TH for JIA patients. METHODS: Chart review of JIA patients who were randomly (based on drug availability) treated with TA or TH IAJI during 2010-2019. Primary outcomes for efficacy were defined as full recovery from arthritis one month after IAJI and a relapse rate of arthritis 3 months after IAJI. Primary outcome for safety was defined as the occurrence of adverse events (AEs) during the follow up period after IAJI. RESULTS: Overall, 292 joints of 102 JIA patients were treated (138 TA/154 TH joints). Complete recovery after one month was documented in 107 (69.6%) of TA treated joints and 96 (69.5%) of TH treated joints (P = 0.232). However, rate of relapse after 3 months was significantly higher for TA treated joints (27 (20.1%) vs. 13 (8.8%), respectively, P < 0.01). No AEs were documented except minor scars at four joint injection sites. CONCLUSION: The recovery from arthritis was similar (~ 70%) with both regimens, however relapse rate was more than double in TA as compared to TH injected joints. These findings are important due to a contemporary shortage of TH in the US market.

Rheumatic fever in a developed country - is it still relevant? A retrospective, 25 years follow-up.

BACKGROUND: Our aims were to clinically and epidemiologically characterize rheumatic fever (RF) in the current era in Israel. Although there has been a steady decline in the incidence of RF in the western world, evidence of disease resurgence in developed countries continues to be published. The paucity of recent epidemiological data prompted our study. METHODS: Medical files were retrospectively reviewed for all children with RF in our tertiary pediatric university-affiliated hospital from 1993 to 2017. Main outcome measures were patients and disease related characteristics, incidence trends, risk factors, disease course, relapse rates and secondary prophylaxis. RESULTS: The cohort included 307 children. Sixty-four percent presented with arthritis, interestingly including hips and small joints of hands and feet at presentation, 52% presented with carditis. Severe carditis developed in 31 patients (19.5%), of whom 21 (13.2% of all carditis patients) acquired heart failure, 5 required intensive care monitoring, with one recent death. The percentage of patients with acute carditis of the overall RF patients remained relatively stable. Thirty-two patients (10% of patients with RF) relapsed, including 11 with a cardiac relapse (3.6% of all cardiac patients). The recurrence rate of RF continued to rise up to 9 years from the initial episode. One of 147 patients (< 0.7%) with a non-cardiac initial presentation had carditis at relapse. CONCLUSION: RF and rheumatic heart disease remain an important cause of morbidity and mortality including developed countries, with relapse rate continuing after 9 years of prophylaxis. Presentation of small joints as well as hips, although uncommon, should not exclude the diagnosis.

Magnetic resonance findings may aid in diagnosis of protracted febrile myalgia syndrome: a retrospective, multicenter study.

BACKGROUND: Protracted febrile myalgia syndrome (PFMS) is a rare complication of Familial Mediterranean fever (FMF). The diagnosis is based on clinical symptoms and is often challenging, especially when PFMS is the initial manifestation of FMF. The aim of this report was to describe the magnetic resonance imaging (MRI) findings in pediatric patients with PFMS. RESULTS: There were three girls and two boys ranging in age from 6 months to 16 years, all of Mediterranean ancestry. Three had high-grade fever, and all had elevated inflammatory markers. MRI of the extremities yielded findings suggestive of myositis, which together with the clinical picture, normal CPK levels, and supporting family history of FMF, suggested the diagnosis of PFMS. Out of most common MEFV mutations tested, one patient was homozygous for M694V mutation, three were heterozygous for M694V mutation, and one was compound heterozygous for the M694V and V726A mutations. CONCLUSIONS: MRI may serve as an auxiliary diagnostic tool in PFMS.

PFAPA flares observed during COVID outbreak: can emotional stress trigger PFAPA attacks? A multicenter cohort study.

OBJECTIVE: It is common knowledge among clinicians who treat PFAPA (Periodic Fever, Aphthous Stomatitis, Pharyngitis, Adenitis) patients that emotional stress can trigger PFAPA attacks similarly to other autoinflammatory diseases. However, it has never been proved scientifically. Our aim was to examine whether emotional stress serves as a trigger for PFAPA attacks. METHODS: Patients aged 3-12 years, with active PFAPA, from two Israeli medical centers were enrolled to this study. Patient's parents were reached via phone calls in two occasions: a stressful period related to the COVID-19 pandemic restrictions and a less stressful period. In both times they were asked to report occurrence of PFAPA attacks in the preceding 2 weeks. The relative stress levels of the two periods were validated by an emotional distress scale questionnaire. The significance level was set at 0.05. RESULTS: Mean age was 7.28 ± 2.7 for the 99 paediatric patients enrolled in the study. Scores for the mean emotional distress questionnaire were statistically significant higher in the stressful period compared to the less stressful period (35.6 ± 8.1 vs. 32.1 ±7.7, respectively, P = 0.047). In the stressful period, 41 (38.7%) reported at least one attack during the preceding 2 weeks, compared to 24 (22.6%) in the less stressful period (p = 0.017). CONCLUSION: PFAPA flares during COVID-19 outbreak are described. This study is the first to suggest that emotional stress is associated with PFAPA attacks.

Case Series of Myocarditis Following mRNA COVID Vaccine Compared to Pediatric Multisystem Inflammatory Syndrome: Multicenter Retrospective Study.

INTRODUCTION: Since the development of COVID-19 vaccines, more than 4.8 billion people have been immunized worldwide. Soon after vaccinations were initiated, reports on cases of myocarditis following the second vaccine dose emerged. This study aimed to report our experience with adolescent and young adults who developed post-COVID-19 vaccine myocarditis and to compare these patients to a cohort of patients who acquired pediatric inflammatory multisystem syndrome (PIMS/PIMS-TS) post-COVID-19 infection. METHODS: We collected reported cases of patients who developed myocarditis following COVID-19 vaccination (Pfizer mRNA BNT162b2) from all pediatric rheumatology centers in Israel and compared them to a cohort of patients with PIMS. RESULTS: Nine patients with post-vaccination myocarditis were identified and compared to 78 patients diagnosed with PIMS. All patients with post-vaccination myocarditis were males who developed symptoms following their second dose of the vaccine. Patients with post-vaccination myocarditis had a shorter duration of stay in the hospital (mean 4.4 ± 1.9 vs. 8.7 ± 4.7 days) and less myocardial dysfunction (11.1% vs. 61.5%), and all had excellent outcomes as compared to the chronic changes among 9.2% of the patients with PIMS. CONCLUSION: The clinical course of vaccine-associated myocarditis appears favorable, with resolution of the symptoms in all the patients in our cohort.

Pyoderma gangrenosum-like ulceration as a presenting feature of pediatric granulomatosis with polyangiitis.

BACKGROUND: Granulomatosis with polyangiitis (GPA) is an anti-neutrophilic cytoplasmic antibody-associated vasculitis affecting small to medium-sized vessels and involves most commonly the kidneys and the respiratory tract. Skin involvement can be seen in up to 50% of children with GPA and is the initial presenting symptom in 7.7%. Pyoderma gangrenosum (PG)-like ulcers are rarely described as a skin manifestation in GPA and very few cases have been reported previously in children. CASE PRESENTATION: We describe 3 new pediatric cases of GPA with PG-like ulcerations. The median age at first symptom was 15 years. Two patients had PG-like ulceration as their initial presentation; additional symptoms eventually led to the diagnosis of GPA 2-24 months later. In 1 case, proteinase 3 (PR3) was negative when first tested, but converted to positive when systemic symptoms emerged; in the other 2 cases PR3 was positive at presentation. All 3 patients had prominent facial lesions. None of the patients responded to treatment with antibiotics or medications commonly used to manage PG, including corticosteroids and cyclosporine. All patients had excellent responses to rituximab. An electronic database literature review was performed and 4 previously reported cases were identified. We assessed the clinical characteristics, serology, and response to treatment of the previously reported and our newly diagnosed cases. CONCLUSION: PG-like ulceration is a rare presentation of pediatric GPA which may precede classic systemic GPA symptoms. The predominance of facial ulcer, granulomatous and neutrophilic inflammation on skin biopsy and lack of response to PG treatments are characteristic of GPA-associated PG-like ulcers. Our review suggests that treatment with rituximab may be needed to improve the skin lesions. Recognizing that PG-like ulcerations can occur in pediatric GPA may result in timely diagnosis, appropriate treatment and improved prognosis.

Pan-cancer single-cell RNA-seq identifies recurring programs of cellular heterogeneity.

Cultured cell lines are the workhorse of cancer research, but the extent to which they recapitulate the heterogeneity observed among malignant cells in tumors is unclear. Here we used multiplexed single-cell RNA-seq to profile 198 cancer cell lines from 22 cancer types. We identified 12 expression programs that are recurrently heterogeneous within multiple cancer cell lines. These programs are associated with diverse biological processes, including cell cycle, senescence, stress and interferon responses, epithelial-mesenchymal transition and protein metabolism. Most of these programs recapitulate those recently identified as heterogeneous within human tumors. We prioritized specific cell lines as models of cellular heterogeneity and used them to study subpopulations of senescence-related cells, demonstrating their dynamics, regulation and unique drug sensitivities, which were predictive of clinical response. Our work describes the landscape of heterogeneity within diverse cancer cell lines and identifies recurrent patterns of heterogeneity that are shared between tumors and specific cell lines.