Mendelian susceptibility to mycobacterial disease (MSMD), caused by IL12RB1 or IL12B mutations, typically presents with intra-cellular infections such as BCG-adenitis or Salmonella. Rarely, patients with IL12RB1/IL12B defects can exhibit cutaneous manifestations such as Henoch-Schonlein purpura (HSP). This study aimed to evaluate such vasculitic manifestations in genetically confirmed cases with MSMD in India and review the literature for similar associations. We included nine patients with genetically proven MSMD presenting with features of HSP-like small vessel vasculitis from pediatric immunology clinics across three tertiary care centers in India. Clinical, laboratory, histopathological, and genetic data were recorded using a structured proforma. Skin biopsy findings, IgA levels, renal involvement, and infection history were analyzed. Additionally, a literature review was performed using PubMed, Scopus, and Google Scholar databases to identify similar reported cases. In our cohort, eight patients had IL12RB1 defect, and one had IL12B defect. All had maculopapular purpuric rash in lower limbs, predominantly in the anterior aspect of legs and posterior thighs resembling the rash of HSP. Leukocytoclastic vasculitis was observed in 77.7% patients (n = 7), with two out of five had IgA deposits in dermo-epidermal junction. Concurrent infections due to Salmonella sp. and Pandorea apista were documented in 44.4% (n = 4) and 22.2% (n = 2), respectively. Treatment focused on antimicrobial therapy led to clinical improvement. The HSP-like vasculitic rash usually occurred in setting of underlying bacterial infections in patients with particularly IL12RB1/IL12B defects. These skin lesions can also be considered as one of the potential clinical clues for underlying IL12RB/IL12B defects.

Kawasaki disease (KD) is associated with long-term vascular sequelae, including persistent endothelial abnormalities. Data on laboratory-based markers of oxidative stress during long-term follow-up of KD patients from developing countries are limited. This study aimed to evaluate extracellular nitric oxide metabolites and neutrophil-derived reactive oxygen species (ROS) in patients with KD during follow-up and to explore their associations with coronary artery abnormalities (CAAs). In this prospective, single-centre study, 62 children with KD and 20 age- and gender-matched healthy controls (HC) were enrolled. KD patients were stratified into three groups based on time since diagnosis and further categorised by the presence or absence of CAAs. Serum nitrite and nitrate levels were measured as indicators of extracellular nitric oxide metabolism. Neutrophil ROS production was assessed using a dihydrorhodamine-123 flow cytometric assay. Serum nitrite levels were comparable across the 3 groups (Group 1: 3.46 ± 1.64; Group 2: 5.04 ± 2.55; Group 3: 5.22 ± 3.00) and HC (3.33 ± 1.98) (p = 0.06). The serum nitrate levels in KD patients across all three groups (Group 1: 63.07 ± 41.32; Group 2: 58.63 ± 27.12; Group 3: 64.57 ± 26.36) were also comparable to HC (57.49 ± 8.68) (p = 0.43). In subgroup analysis, serum nitrate levels and serum nitrite levels in KD patients with CAAs and without CAAs were comparable (Group 1: p = 0.60; Group 2: p > 0.99; Group 3: p = 0.10) and (Group 1: p > 0.99; Group 2: p > 0.99; Group 3: p = 0.90), respectively. Neutrophil ROS production (ΔMFI) was increased in KD patients, with a significant rise observed in the intermediate follow-up group 2 (> 1.5–3 years) compared with healthy controls (p = 0.03). No significant correlations were found between oxidative stress markers and systemic inflammatory parameters. Children with KD exhibit persistent oxidative stress during follow-up, as evidenced by increased neutrophil ROS production, indicating ongoing cellular oxidative activity. Elevated ROS may serve as an accessible biomarker for CAAs and long-term cardiovascular risk in KD patients on follow-up.

Objectives: To analyse the clinical profile of children with Juvenile Dermatomyositis (JDMS) who had thrombocytopenia (<150 & times; 109/L) at disease onset and compare them with patients who had normal platelet counts. Methods: Children diagnosed to have JDMS based on modified Bohan and Peter criteria and being followed up in a tertiary care referral hospital in North India were analysed. Collected data included clinical profile, laboratory investigations, treatment details, and outcome. Results: We analysed 131 patients with JDMS. Fourteen amongst these (10.7%) had thrombocytopenia at initial diagnosis. None of them had evidence of sepsis, overlap syndrome or macrophage activation syndrome. Median time for improvement of thrombocytopenia was 1.4 months (IQR: 0.4-6 months). Patients with thrombocytopenia had late onset of disease (9.9 vs. 6 years, P = .008). Amongst the cutaneous manifestations, periorbital swelling [10 vs. 49, P = .047] and anasarca [3 vs. 2, P = .009] were seen more with thrombocytopenic patients. The number of patients with severe muscle disease (28 vs. 48, P = .001), respiratory muscle weakness [5 vs. 6, P = .002], pharyngeal weakness [9 vs. 40, P = .040], and gastrointestinal vasculopathy [5 vs. 1, P = .001] was high in the thrombocytopenic group. Median time required to achieve remission was longer in the thrombocytopenic group (8 vs. 4.5 months, P = .011). Mortality rate was also high in the thrombocytopenic group [3 (21.45%) vs. 7 (5.9%)].Results: We analysed 131 patients with JDMS. Fourteen amongst these (10.7%) had thrombocytopenia at initial diagnosis. None of them had evidence of sepsis, overlap syndrome or macrophage activation syndrome. Median time for improvement of thrombocytopenia was 1.4 months (IQR: 0.4-6 months). Patients with thrombocytopenia had late onset of disease (9.9 vs. 6 years, P = .008). Amongst the cutaneous manifestations, periorbital swelling [10 vs. 49, P = .047] and anasarca [3 vs. 2, P = .009] were seen more with thrombocytopenic patients. The number of patients with severe muscle disease (28 vs. 48, P = .001), respiratory muscle weakness [5 vs. 6, P = .002], pharyngeal weakness [9 vs. 40, P = .040], and gastrointestinal vasculopathy [5 vs. 1, P = .001] was high in the thrombocytopenic group. Median time required to achieve remission was longer in the thrombocytopenic group (8 vs. 4.5 months, P = .011). Mortality rate was also high in the thrombocytopenic group [3 (21.45%) vs. 7 (5.9%)]. Conclusion: Children with thrombocytopenia at onset in JDMS showed severe disease activity, high rates of relapse, and mortality. Thrombocytopenia at disease onset in JDMS could be considered as a potential laboratory marker to predict a severe disease course and outcome.

Background and objectives: Global estimates identify about 7,000 rare diseases affecting 6-8% of the population, with 80% being genetic. India lacks comprehensive data on their prevalence, distribution, and natural history. Inborn errors of immunity (IEI) registry was developed by Indian Council of Medical Research (ICMR) as part of a comprehensive multi-centric 'National Registry for Rare and Other Inherited Disorders', from centres which expressed interest in contributing to this national database in 2019. This study aims to establish an Indian rare-disease registry to assess disease burden, collect clinical and demographic data, understand natural history, support research on underlying mechanisms, create cohorts for evaluating therapies and orphan products, and strengthen connections among patients, families, and clinicians to improve comprehensive care across the country effectively. Methods: After ethics approval from the participating centres, data were collected in a structured format developed jointly by ICMR-National Institute of Immunohaematology, Mumbai and Postgraduate Institute of Medical Education and Research, Chandigarh, identified as nodal centres for inborn errors of immunity (IEI) by ICMR. Cases with molecular confirmation of diagnosis or those satisfying the European Society for Immunodeficiencies (ESID) registry working definition in absence of molecular confirmation were included. The Data were compiled in excel format and analysed using Epi Info v7.2.5.0. Results: Data for 676 patients enrolled between January 2019-October 2024 from six participating centres including ICMR-NIIH Mumbai, PGI Chandigarh, Apollo Chennai, JIPMER Pondicherry, Nizams Institute Hyderabad, and Sir Gangaram Hospital Delhi was analysed. Immunodeficiencies affecting cellular and humoral immunity (CID) and CID with associated or syndromic features (n=187,27.6%), predominantly antibody deficiency (n=146,21.6%), congenital defects of phagocyte number or function (n=117,17.3%) were the most frequent IEIs. The median age of presentation was 16 (IQR 4,63) months and diagnostic delay of 16 (IQR 3,55) months. The presenting clinical manifestations comprised of recurrent infections (n=459,67.9%), autoimmunity or auto-inflammation (n=292,43.2%), adverse effect following immunisation (n=38,5.6%), and malignancy (n=5,0.73%). 103/146 (70%) patients with antibody deficiency received IVIG and 90 (13.3%) IEI patients underwent hematopoietic stem cell transplant. On follow up, 118 (17.4%) patients died due to infections by 2024. Interpretation and conclusions: The IEI registry developed by ICMR as an attempt to maintain a patient database gives us insights on the demographic, clinical presentation, diagnostic-delay and treatment outcomes of these disorders.

Background Myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) are increasingly being identified in juvenile inflammatory myositis (JIIM). The current study's objective was to characterize the incidence and clinical-phenotypic profile of MSA/MAA in a cohort of JIIM from North India. Methods We reviewed the medical records of the Pediatric Rheumatology Clinic of a tertiary care referral centre in Chandigarh, North India (1992 to 2024) and analysed the clinical details of children with JIIM. MSA/MAAs were assayed using a 16-antigen kit immunoblot assay (Euroline Autoimmune Inflammatory Myopathies 16 Ag, Euroimmune, Lübeck, Germany). Results Of the 173 patients of JIIM in our cohort, assay for MSA/MAA was performed in 113 patients which included juvenile dermatomyositis (n=89), clinically amyopathic dermatomyositis (n=8), overlap myositis (n=13), and juvenile polymyositis (n=3). Autoantibody positivity was seen in 72.5% (82/113; MSA =70, MAA=12) of the children, with anti-NXP2 (n=24) being the most common followed by anti-MDA5 (n=14), anti-TIF-1γ (n=12), anti-Mi 2 (n=9) in that order. Patients with NXP2 positivity were younger at onset [3.15 years; (1.2-11.88 years) p=0.015], had severe muscle weakness at onset (p=0.04) and persistent calcinosis (p=0.004) in follow-up. Patients with anti-TIF1γ antibody were observed to have persistent skin lesions (p <0.001) during follow-up. Incidence of arthritis (p=0.001), inverse Gottron papules (p=0.003), skin ulceration (p=0.065), oral ulcers (p=0.012), and ILD (p<0.001) were high in anti-MDA5-JDM. Conclusion Anti-NXP2 antibody is the most common MSA noted in our North Indian cohort of JIIM. The findings emphasize the importance of region-specific data in understanding disease variability and guiding management.

Autoimmune manifestations occur in 25-75% of patients with Wiskott-Aldrich syndrome (WAS), commonly including autoimmune hemolytic anemia, skin vasculitis, IgA nephropathy, arthritis, and inflammatory bowel disease. Large vessel vasculopathy is rarely reported in WAS. We present a review of children with WAS and evidence of large vessel vasculopathy at our center, analyzing clinical, radiological, immunological, and genetic data. Among 80 patients diagnosed with WAS over two decades, four children (aged 10-18 years) developed large vessel vasculopathy. Two had classical WAS with bleeding, recurrent infections, and eczema since infancy, while two had milder phenotypes and presented for the first time during this illness. Clinical features included chest pain and heart failure, abdominal pain, upper limb claudication, and differential blood pressure. Imaging demonstrated aneurysmal dilatation of the aorta and its major branches. Epstein-Barr virus viremia was detected in three patients. All received intravenous immunoglobulin and immunosuppressive therapy; none could undergo hematopoietic stem cell transplantation (HSCT), and three patients died. Large vessel vasculopathy is a rare but life-threatening complication of WAS, underscoring the importance of early recognition and timely consideration of HSCT.

Intravenous immunoglobulin (IVIg) is the standard of care for the treatment of Kawasaki disease (KD) and should be administered within 10 days of the onset of fever. Management guidelines for children with KD who defervesce spontaneously are not clear. In this study, we analysed patients with KD diagnosed between 1994 and 2024 at our centre who had defervesced spontaneously, had normal acute-phase reactants, and underwent echocardiographic examination, and in whom IVIg had not been administered. We reviewed the records of patients with KD from January 1994 – December 2024. The diagnosis of KD was based on standard guidelines. Patients with KD were said to be in spontaneous defervescence when they remained afebrile for ≥ 48 h, had normal acute-phase reactants [C-reactive protein (CRP), Erythrocyte sedimentation rate (ESR)] and no coronary artery abnormalities (CAAs) on echocardiography at presentation, and when IVIg was not administered. Patients with spontaneous defervescence were subdivided into (i) early defervescence (Ed-KD), if the interval between onset of symptoms and defervescence was < 10 days, and (ii) late defervescence (Ld-KD), if the duration between onset of symptoms and defervescence was ≥ 10 days, respectively. Details of the clinical profile, laboratory investigations, and echocardiography findings were obtained from the records. Of the 1499 patients with KD enrolled during the study period, 115 patients (7.7

BACKGROUND:Kawasaki disease is the leading cause of acquired heart disease in children worldwide. Previous studies from Chandigarh, India, documented a rising incidence until 2019. The COVID-19 pandemic, with its infection-control measures and emergence of multisystem inflammatory syndrome in children, disrupted established epidemiological trends. We aimed to evaluate the impact of the pandemic on incidence, clinical features, and coronary outcomes in children with Kawasaki disease in the Union Territory of Chandigarh. METHODS:This study was conducted at the tertiary care teaching institute in North-West India, from January 2020 to December 2024. Demographic, clinical, laboratory, and echocardiographic data were collected. Population estimates were derived from national census projections, and annual incidence rates were calculated for children <5 years and <15 years. Temporal and seasonal trends were analysed using regression models and Chow tests. FINDINGS:A total of 442 children with Kawasaki disease were diagnosed during the study period-of these, 60 (median age 40.5 months, 62% male, 63% complete, and 37% incomplete Kawasaki disease) were residents of Chandigarh. Incidence declined markedly during the pandemic (1.7 and 3.4 per 100,000 children <5 years in 2020 and 2021, respectively), followed by a rebound in 2022 (8.4) and 2023 (5.8), and a sharp rise in 2024 (13.9), the highest incidence recorded to date in Chandigarh. Coronary artery abnormalities were detected in 13% of patients, with 3.3% showing persistent lesions at 6 weeks. No deaths occurred, and seasonal patterns remained unchanged compared with 2015-2019. INTERPRETATION:Kawasaki disease incidence in Chandigarh declined transiently during the COVID-19 pandemic but rebounded sharply post-pandemic, exceeding the highest previously reported estimates. Despite fluctuations, clinical features and coronary outcomes remained stable. These findings reinforce Kawasaki disease as an endemic childhood vasculitis in Chandigarh, India, and highlight the need for ongoing surveillance and early recognition as an important contributor to acquired heart disease burden in children.

OBJECTIVES:To investigate the genetic basis of early-onset systemic lupus erythematosus (EOSLE) in a large Indian pediatric SLE (pSLE) cohort. METHOD:This prospective observational study investigated monogenic causes in 97 of 365 pSLE patients. Inclusion criteria for the study comprised patients with EOSLE (age ≤8 years) and/or those with a clinical suspicion of monogenic lupus. Monogenic cause was suspected in 97 patients. Genetic screening using targeted next-generation sequencing on the Ion S5 system in 55 of 97 patients [complement defect gene panel in 28 and type 1 interferonopathy gene Interferon (IFN)+ Adaptive Immunity panel in 27] was performed. The remaining 42 patients underwent whole-exome sequencing (WES). RESULTS:Among 97 patients, 22 (22.68%; 11 boys and 11 girls) were found to carry pathogenic variants. Median symptom onset in monogenic cases was 2 years (range: 2 months to 9 years). Monogenic lupus was identified in both EOSLE and older children with strong clinical suspicion. EOSLE patients showed a higher diagnostic yield (28.4%) compared with older children (4.4%). Consanguinity was reported in 7/22 (31.8%) patients. Variants were found in C1QA (n = 7), C1QC (n = 2), C1QB (n = 1), C1R (n = 1), C3 (n = 2), ACP5 (n = 2), STING1, DNASE2, ADAR, TREX1, DNASE1L3, PEPD and SLC7A7 (each n = 1). CONCLUSIONS:Monogenic causes were found in at least 6.1% of the overall cohort of pSLE and in 22.7% of genetically screened cases, with the highest yield in EOSLE (28.4%). C1QA was the most common single-gene defect (7.2%). These findings underscore the value of genetic testing in pSLE, especially those with EOSLE or suggestive clinical features.

PURPOSE:To analyse the evolution of uveitis diagnosis over a 10-year period, emphasizing the change in etiological diagnosis, and the factors associated with recurrences. DESIGN:Retrospective chart review. METHODS:A total of 15,000 patients with uveitis presented at our tertiary care institute in North India between 1992 and 2023. Of these,123 patients completed 10-year follow-up and were included in the study. The data of patients was collected on an offline purpose-built uveitis registry portal: Ocular Autoimmune Systemic Inflammatory and Infectious Study(OASIS). RESULTS:The study included 123 patients (48.78% males; mean age: 29.11 ± 15.22 years). The most common anatomical and etiological diagnosis at presentation were anterior (49/123,34.96%) and idiopathic(59/123,47.97%) uveitis respectively. At the end of 10 years, anterior uveitis remained the most common anatomical diagnosis (43/123,39.83%) while the most common etiological diagnosis was immune-mediated uveitis (50/123,40.65%). An etiological diagnosis could be established in 50.85% (30/59) of patients initially labelled as idiopathic. Tuberculous uveitis (39/44, 88.63%) and Juvenile Idiopathic Arthritis associated uveitis (16/49, 32.65%) were the commonest infectious and immune-mediated aetiologies at the 10-year follow-up. Ninety-six (80.67%) patients experienced multiple episodes of ocular inflammation with a mean recurrence rate of 0.386 ± 0.24 recurrences/year. Anterior uveitis (p = 0.01), the change in etiological diagnosis after the first year (p = 0.03), positive HLA-B27 at baseline (p = 0.04), and the diagnosis of a systemic disease prior to the onset of uveitis were associated with higher recurrences rates (p = 0.03). CONCLUSION:Over 10-year of follow-up, half of the uveitis diagnoses evolved from idiopathic to specific infectious or immune-mediated aetiologies. Our results indicate that patients with a high recurrence rate may benefit from re-evaluation to find the definitive cause of uveitis.

Background:Hereditary angioedema (HAE) is characterized by unpredictable acute attacks that impair the patient's quality of life (QoL) not only due to the impact on functional abilities caused by edema but also due to pain and other symptoms, including fatigue, nausea, and vomiting. Objectives:QoL studies in patients with HAE have not been carried out in the Indian subcontinent. Hence, we carried out this study to assess the QoL and to identify factors associated with impaired QoL in patients with HAE. Methods:This was a cross-sectional observational study carried out in confirmed cases of HAE, aged >18 years, using angioedema QoL score and angioedema control test. Results:We enrolled 135 patients with HAE (aged 18-80 years) with a mean age of 40.93 years. We observed that the QoL directly correlates with angioedema control and is also affected by other factors such as gender, duration of follow-up, and the frequency of episodes. Genitalia swelling, positive family history, and presence of mortality due to HAE in the family also significantly impact the QoL of patients with HAE. In addition, patients with type 1 HAE reported a poorer QoL as compared to patients with type 2 HAE. Conclusion:We report the QoL of patients with HAE from settings where none of the first-line medications are available. Results of the study suggest that disease control is the most important factor that influences the QoL.

The present study aimed to evaluate lymphoid defects in patients with specific IEIs (n = 28) using a 12-antibody 9-color single-tube flow cytometry assay. The lymphoid defects (lymphocyte counts below the reference range) were significantly higher in XLA patients (p-0.0002), CVID patients (p-0.00022), WAS patients (p- < 0.001), HIES patients (p- < 0.001), CHS patients (p < 0.001), and CGD patients (p < 0.0002) than age-matched controls. The lymphoid defects (lymphocyte counts above the reference range) were significantly higher in LAD-1 than age-matched controls (p < 0.001). In patients with XLA, the NK cells were reduced in 50

Background: Kawasaki disease (KD) is a systemic vasculitis and the leading cause of acquired heart disease in children. Early identification of coronary artery abnormalities (CAAs) is crucial to guide treatment and improve outcomes. While transthoracic 2D echocardiography (TTE) remains the first-line imaging modality, it has limitations, particularly in visualizing distal coronary artery segments and detecting thrombi. Computed tomography coronary angiography (CTCA) offers enhanced visualization, but its role at initial presentation of KD remains underexplored. Methods: We reviewed the records of 71 children with KD who underwent CTCA at their initial presentation at a tertiary center between November 2013 and December 2024. The CTCA findings were compared with those of TTE. CTCA was performed after stabilization using radiation-minimized protocols. Results: Of 71 patients, 62 had CAAs on baseline TTE. CTCA confirmed CAAs in 39 patients, identified additional lesions in 23, and detected distal aneurysms and coronary branch involvement missed by TTE. In 20 patients with initially abnormal TTE, CTCA demonstrated normal coronaries, facilitating treatment de-escalation. CTCA identified coronary thrombi missed on TTE in two patients and congenital coronary anomalies in three patients. CTCA findings led to modification of therapy in multiple cases. Conclusions: CTCA is a valuable adjunct to TTE in evaluating coronary artery involvement at the time of initial presentation of children with KD. Given its superior visualization of the entire length of coronary arteries, CTCA has a vital role in therapeutic decision-making in KD.

BACKGROUND:The exact pathogenesis of Kawasaki disease (KD) is unknown despite extensive research in the area. Several studies have also implicated CD8+ T lymphocytes in the pathogenesis of KD. However, studies on the activation status of T lymphocytes have shown conflicting results. METHODS:In this prospective study, early (CD69) and late activation (HLA-DR) markers were assessed in T lymphocytes by flow cytometry. We assessed serum levels of soluble CD25 (sCD25) by enzyme-linked immunosorbent assay. We compared these activation markers between children with KD (n = 10), febrile controls (n = 9), and healthy controls (n = 10). Furthermore, we studied the HLA-DRA and HLA-DRB gene expression in subgroups of KD with or without coronary artery aneurysms (CAAs). RESULTS:A significantly higher percentage of CD69 in CD3+ and CD3 + CD4+ T lymphocytes was noted in KD and febrile controls compared with healthy controls. We found no significant increase in late activation marker HLA-DR in CD3, CD3 + CD4+, and CD3 + CD8+ lymphocytes between KD, febrile, and healthy controls. We observed higher levels of sCD25 in KD and febrile controls than in healthy controls. Longitudinal follow-up in KD showed a decreasing trend of CD69 expression in CD3 + CD8+ lymphocytes and sCD25 levels over time. HLA-DRA and HLABRB expression was comparable between children with CAAs and those without CAAs. CONCLUSION:Our study showed early but not late activation of T lymphocytes in children with KD. Markers of lymphocyte activation do fall with subsidence of systemic inflammation following intravenous immunoglobulin therapy in KD.

Background : Rare diseases are a diverse set of disorders that individually affect a relatively small number of individuals but collectively form an important public health problem globally and in India. These diseases are often complex and challenging to diagnose and treat, significantly impacting lives of those affected and their families. Limitation in the knowledge that persists for most rare diseases is due to the dearth of reliable data on rare diseases in India. A patient registry is a powerful tool for systematically collecting data and creating a database necessary for informing healthcare policy and its execution. The National Registry for Rare and Other Inherited Disorders (NRROID) is a prospective hospital-based study initiated by the Indian Council of Medical Research in 2019 currently at 23 centres in India, to gather comprehensive data on selected rare diseases, including natural history, treatment, and disease outcomes, and to create a database to support further research and assist in the development of policies aimed at improving healthcare outcomes for rare disease patients. Currently, six broad groups of disorders, namely, storage disorders, inborn errors of metabolism (small molecule), skeletal dysplasias, primary immunodeficiencies, neuromuscular disorders, and hematological disorders have been included for reporting in the registry. Presently, NRROID provides valuable data related to demography, clinical features, diagnosis, management, and some other aspects of rare diseases. Results : Till February 2025, registry enrolled 15,369 patients under the 6 broad rare disease groups encompassing 231 rare diseases. Regional distribution depicts that the highest number of rare disease patients enrolled are from North India (34%) followed by South India (29%). Neuromuscular disorders (6307) account for the highest number of patient enrollments, followed by Thalassemia (3276) and Storage disorders (1632). A significant predominance of male patients (75%) has been reported in the registry, and the majority of patients (81.15%) fall in the pediatric age group under 18 years of age. Conclusion : This article summarizes the implementation of India’s first national rare disease registry and highlights key demographic and clinical trends. The NRROID provides foundational data to inform policy, research, and clinical care for rare disease patients in India.

Etiology of Kawasaki disease (KD) remains an enigma despite more than 50 years of extensive research. There is evidence that concurrent infections may play a role in the pathogenesis of KD. The present study reports various infections identified in a large cohort of patients with KD in Northwest India. We reviewed case records of patients with KD from January 1994 to February 2020. Patients with KD identified to have concurrent infection at presentation were analyzed in detail. Of 878 cases of KD during this period, 88 (60 boys, 28 girls; 64 incomplete KD, 24 complete KD) had evidence of concurrent infection. Infective manifestations included superficial and deep-seated abscesses (27.45

Purpose:Hemophagocytic lymphohistiocytosis (HLH) is a fatal systemic inflammatory syndrome caused by a wide array of causes, which may be detected on 18F fluorodeoxyglucose positron emission tomography/computed tomography (18F FDG PET/CT). This study explores the utility of 18F FDG PET/CT in HLH. Materials and Methods:Retrospective data of HLH patients referred for whole-body 18F FDG PET/CT were analyzed for abnormal findings, and quantitative analysis using standardized uptake value (SUV), spleen-to-liver ratio (SLR), and bone-to-liver ratio (BLR) was done and correlated with laboratory parameters, bone marrow (BM) findings, and final diagnosis. Results:Twenty-four patients (median age 22 years [interquartile range 13-34]) were included in the study. The most common cause of HLH was infection (33%), malignancy (29%), and autoimmune disorders (13%), and five patients had primary HLH. 18F FDG PET/CT was positive in 22/24 patients (92%). Hepatomegaly and splenomegaly were observed in 22 patients (92%) and 16 patients (67%), respectively, with six (25%) showing splenic lesions. Splenic uptake > liver was observed in 62.5% of patients and BM uptake > liver uptake in 50% of patients. There was no significant difference in median BM uptake (SUVmax 4.0 vs. 3.5, P = 0.6) and BLR (1.475 vs. 1.514, P = 0.4) in patients with and without HLH on marrow sampling, but a significant difference was observed in hypercellular vs. normocellular/hypocellular marrow (SUVmax 5.1 vs. 3.2, P = 0.019 and BLR 1.58 vs. 0.82, P = 0.043). A significant positive correlation was observed between splenic and BM uptake (r = 0.501, P = 0.013), BLR and SLR (r = 0.623, P = 0.001), C-reactive protein levels with BLR (r = 0.731, P = 0.001), and SLR (r = 0.594, P = 0.015), respectively. In 11 patients who underwent targeted sampling from most hypermetabolic sites, it helped reach the final diagnosis or eliminate malignant causes. Conclusion:18F FDG PET/CT has a high diagnostic yield in HLH with the potential to detect its underlying causes and may be considered in the diagnostic algorithm of HLH.