Endogenous Fungal Endophthalmitis: A Single-Center Retrospective Study and Review of the Literature

PURPOSE

To evaluate factors that inform systemic antifungal choices in patients with endogenous fungal endophthalmitis (EFE).

DESIGN

Single-institution retrospective case series.

METHODS

Charts of EFE patients from 2010 to 2023 were reviewed. Patients treated systemically for EFE with a minimum of 14 days of follow-up were included. Outcome measures included time to improvement in vitritis or chorioretinitis, systemic therapy modification, and need for surgical intervention.

RESULTS

A total of 20 eyes of 16 patients were included. Candida species were most common (43.8%), followed by culture-negative EFE (37.5%) and Aspergillus species (18.8%). In all, 90% of eyes had vitritis and/or macula-involving chorioretinitis. The majority of Candida infections (60%) or culture-negative EFE (75%) were treated initially with oral antifungals. Patients with a history of immune compromise, positive fungal culture, or positive Fungitell assay were more likely to be treated with early intravenous (IV) antifungal therapy. Two patients required systemic antifungal therapy modification because of worsening chorioretinitis, in 1 case due to voriconazole-resistant Aspergillosis that demonstrated chorioretinal lesion growth despite intravitreal amphotericin B injections and systemic voriconazole, and in the second case due to worsening chorioretinitis from Candida dubliniensis infection that regressed upon switch from oral to IV fluconazole.

CONCLUSIONS

Initial systemic treatment decisions in patients with EFE were driven by systemic culture positivity, systemic symptoms, or comorbidities. Intravitreal antifungal therapy may be insufficient to arrest progression of chorioretinal lesions in some cases. Larger studies are needed to determine whether visible end-organ damage in the form of chorioretinitis may be useful for guiding systemic therapy changes.

Comparative evaluation on wear resistance of metal sleeve, sleeve-free resin, and reinforced sleeve-free resin implant guide: An in vitro study

BACKGROUND

In-office three-dimensional (3D) printers and metal sleeveless surgical guides are becoming a major trend recently. However, metal sleeve-free designs are reported to be more prone to distortion which might lead to variation in the inner diameter of the drill hole and cause deviation and inaccuracy in the placement of the implant. Carbon fiber nanoparticles are reported to improve the properties of 3D printing resin material in industrial application.

AIM

The purpose of the study is to evaluate and compare the wear resistance of 3D-printed implant guides with metal sleeve, sleeve-free, and reinforced sleeve-free resin to the guide drill.

MATERIALS AND METHODS

A total of 66 samples with 22 samples in each group. Three groups including 3D-printed surgical guide with metal sleeve (Group A), without metal sleeve (Group B), an carbon fiber reinforced without metal sleeve (Group C) were included in the study. All samples were evaluated before sequential drilling and after sequential drilling using Vision Measuring Machine. The data were tabulated and statistically evaluated.

RESULTS

The data obtained were statistically analyzed with one-way analysis of variance and posthoc test. The data obtained for wear observed in the samples showed that the wear was highest in Group B with a mean of 0.5036 ± 0.1118 and the least was observed in Group A with a mean of 0.0228 ± 0.0154 and Group C was almost similar to Group A with mean of 0.0710 ± 0.0381. The results showed there was a significant difference between Group B with Group A and C, respectively (P < 0.05). The results showed that there was no significant difference regarding the wear observed between Groups A and C (P > 0.05).

CONCLUSION

The wear observed in the guide with a metal sleeve and carbon fiber reinforced without a metal sleeve was almost similar. The carbon fiber-reinforced guide showed better tolerance to guide drill equivalent to metal sleeve. Thus, carbon fiber nanoparticles reinforced in 3D printing resin have shown improved strength and can be used as a good replacement for a metal sleeve for an accurate placement of the implant.

Virtual clinic for hearing loss and non-pulsatile tinnitus: initial experience of 210 cases

OBJECTIVE

Patients with hearing loss and tinnitus face lengthy waits to be seen in the ENT clinic. SHOEBOX Audiometry is an iPad-based, audiometric screening tool. A virtual hearing loss and non-pulsatile tinnitus clinic involving an ENT specialist virtually assessing cases based on the SHOEBOX audiogram, a patient symptom questionnaire and the primary care referral letter were implemented. This service evaluation explored the outcomes of the virtual clinic in reducing the need for a face-to-face ENT appointment.

METHOD

This was a retrospective service evaluation of the first six months of the virtual hearing loss and non-pulsatile tinnitus clinic.

RESULTS

A total of 210 patients were included: 34.8 per cent (73) were discharged without requiring audiologist assessment or an ENT appointment, 51.9 per cent (109) required formal audiological assessment, 36.7 per cent (77) required imaging and only 13.8 per cent (29) required a face-to-face ENT appointment.

CONCLUSION

A virtual hearing loss and non-pulsatile tinnitus clinic minimised the number of patients requiring a traditional face-to-face clinic appointment within ENT.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Histopathologic spectrum of glomangioma: A clinico-pathologic review

Introduction/Objective

Glomus tumors are mesenchymal neoplasms with glomus body type modified smooth muscle cell differentiation. Most glomus tumors have a benign clinical course. However, rarely, they display malignant histologic features.

Methods/Case Report

We undertook a retrospective study using a natural language search in CoPath to find surgical pathology cases from 1993-2020 containing “glomus” in the pathology diagnosis. All relevant cases were included, and clinicopathologic data were reviewed in detail.

Results (if a Case Study enter NA)

A total of 66 tumors were identified, of which 42 were in female (63.6%) and 24 in male (36.4%) patients. The age at surgery ranged from 22 to 79 years with a median of 47.5. Females were significantly younger than males at presentation (p=0.025) by 8.8±3.8 years. Forty cases (60.6%) were located on the digits, 24 in nonvisceral soft tissue of extremities, trunk, and lip (36.4%), and one each in stomach and breast parenchyma. Sixty-three (95.5%) were benign (of which one recurred locally), 2 (3%) were malignant, and 1 (1.5%) was atypical. Four (6%) were multicentric. One case showed mixed histology (oncocytic and classic features) and one was classified as glomangiomatosis. The malignant cases each presented with a single tumor in lower extremity soft tissue in female patients (aged 33 and 49 years). The tumors measured 0.5 and 1.8 cm respectively and showed marked cytologic atypia in both and increased mitotic activity in the first. They were both completely excised.

Conclusion

The majority of glomus tumors are benign, however 3% are malignant. The most common location is the digits, followed by soft tissue. This tumor is more commonly seen in female patients. Unusual histologic variants such as glomangiomatosis and oncocytic component at times may create some difficulty to reach the diagnosis, especially on small biopsies. Unusual locations such as stomach can lead to a wrong diagnosis such as carcinoid, especially in a small biopsy material.

Acute safety and performance outcomes from the inspIRE trial using a novel pulsed field ablation system for the treatment of paroxysmal atrial fibrillation

Background/Introduction

The inspIRE clinical trial was designed to assess the safety and efficacy of a fully integrated biphasic pulsed field ablation (PFA) system comprised of a multi-channel generator, variable decapolar irrigated loop circular catheter, and mapping system (Figure A) for the treatment of paroxysmal atrial fibrillation (PAF).

Purpose

Using this novel PFA system in a multicentre clinical trial, we present the initial feasibility of electrical pulmonary vein isolation (PVI), procedural performance, and acute safety results.

Methods

inspIRE is a prospective, non-randomized, multi-centre study, planned to enrol up to 550 patients. PVI is performed with the novel, variable loop circular catheter, compatible mapping system and generator. Acute procedural effectiveness (entrance block in all clinically targeted PVs post adenosine/isoproterenol challenge) and the incidence of primary adverse events (PAEs) were assessed. PAEs are defined as the occurrence of cardiac tamponade/perforation, myocardial infarction, stroke/cerebrovascular accident, thromboembolism, transient ischemic attack, permanent phrenic nerve paralysis, pulmonary edema, pericarditis, and any major vascular access complications within 7 days of the ablation procedure. Additionally, any incidence of procedure or device related death, atrio-esophageal fistula, or PV stenosis (related to the ablation procedure or study catheter) within the 12M follow-up period is classified as a PAE.

Results

A total of 35 PAF subjects (age 59.7±10.7 years, 54.3% male) were treated across 5 European sites by 6 operators. Acute procedural success was achieved in 100% of study subjects (Figure B) with zero incidence of PAEs. Mean total procedure time was 82.9±19.9 minutes with 27.0±11.9 minutes of PFA from first to last application. Average fluoroscopy use was 10.6±6.8 minutes and LA dwell time was 45.6±15.3 minutes.

Conclusion

Initial results of the inspIRE trial demonstrate the acute safety and effectiveness of the new integrated IRE circular catheter, mapping system and generator for PVI in PAF patients.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): inspIRE is a company-sponsored study funded by Biosense Webster, Inc. Figure 1. (A) PFA System; (B) PVI Voltage Map

B-Cell/Mixed Phenotype Acute Leukemia Following Lenalidomide Maintenance For Multiple Myeloma: A Study Of Two Cases

Introduction/Objective

The incidence of patients with multiple myeloma (MM) followed by hematologic malignancies as second primary malignancy is around 0.8 – 3.1%. The majority of cases are myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), however, acute lymphoblastic or mixed phenotype leukemia can be rarely observed.

Methods

A retrospective chart review was performed for patients diagnosed with acute lymphoblastic or mixed phenotype leukemia from January 2009 through February 2020. Two patients were identified and the corresponding clinical data were reviewed.

Results

Case 1 was a 74-year old male diagnosed with pre-B ALL 5 years after an IgG Lambda MM. His MM therapy included Bortezomib-based chemotherapy followed by Lenalidomide maintenance. Pre-B diagnosis was confirmed on a pelvic lesion biopsy with sheets of intermediate sized cells (CD45+, PAX5+, CD34+, CD43+, CD10+, BCL6+ and BCL2+). The patient had 4 cycles of HyperCVAD chemotherapy, followed by Blinatumomab and Inotuzumab treatment. Unfortunately, the patient was referred to hospice 2 years after the diagnosis of ALL. Case 2 was a 69-year old male diagnosed with mixed phenotype acute leukemia 8 years after an lgA Lambda MM with del 13q and Trisomy 11. The patient was treated with Bortezomib-based chemotherapy followed by autologous hematopoietic stem cell transplantation (auto-HSCT) and Lenalidomide maintenance. Bone marrow biopsy showed around 79% blasts (CD34+, PAX-5+, CD79a+ and MPO+). Flow cytometry from bone marrow showed 90% precursor B cells, however MPO was negative. Furthermore, a DNTM3A p.T835M missense variant (25-30% fraction) was identified by next generation sequencing (NGS). The patient was scheduled for Hyper-CVAD chemotherapy.

Conclusion

Lenalidomide maintenance following auto-HSCT is considered a standard therapy for MM patients. Recent studies indicate that Lenalidomide maintenance is associated with an increased risk of second primary hematologic malignancies. Although AML and MDS are more commonly seen, ALL and rarely mixed phenotype leukemias can occur.

863Leadless endocardial pacing improves symptoms in patients with failed conventional CRT implant in long term follow up

Funding Acknowledgements

EBR Systems, Inc

OnBehalf

WiSE-CRT and LV-SELECT study and POST-M REGISTRY

Background

The WiSE-CRT (Wireless stimulation endocardial) system has advantages over conventional epicardial CRT. Whenever conventional CRT failed to implant or failed to echocardiographic response, the WiSE-CRT was implanted as part of the WiSE CRT study (N = 13), as part of the LV-SELECT study (N = 35) or as part of the POST-M REGISTRY (N = 117) over the last 8 years. All these studies have reported high rates of clinical and echocardiographic response compared to conventional CRT.

Objectives

The purpose of this analysis was to determine the safety and clinical response in the largest available number of implanted patients (pts) with long term follow up of 2 years and the first, second and third generation of WiSE-CRT devices.

Method

All pts undergoing a WiSE-CRT implantation as part of the WiSE CRT study (N = 13), as part of the LV-SELECT study (N = 35) or as part of the POST-M REGISTRY (N = 117) were analysed (N = 165). Pts were followed-up for 24 months and considered CRT responders if an improvement in NYHA ≥ 1 class from baseline (pre-implant) was achieved.

Results

In total, 165 pts were implanted, demographics include: 68.2 ± 9.6 year’s old, 81.8% male, 49.7% with history of AFib and 54.5% non-ischaemic aetiology. The mean intrinsic QRS duration was 165.0 ± 32.3 msec (28 pts pace-maker dependent). 161 pts had the system successfully implanted with no major complications, 3 (1.8%) pts developed a pericardial effusion and 1 (0.6%) electrode was lost during implantation and recovered surgically. During the 24-month follow-up period, 20 (12.1%) pts died from any cause, 4 (2.4%) pts developed TIA or Stroke and 15 (9.1%) pts had pocket or transmitter infection. There was a significant improvement in NYHA functional class in 63.6% pts and an average improvement of -26.1 (-45.1, -7.1) msec in QRS duration.

Conclusion

Despite a history of failed conventional CRT implantation, pts undergoing CRT upgrades with a WiSE-CRT have a high success rate and a complication rate similar to previously described. In addition endocardial LV pacing led to symptomatic improvements in 64% of patients reaching the 24 month of follow up.

Abstract Figure 1: Forest Plot NYHA Responder Rat

P1033Impact of workflow modifications in atrial fibrillation ablation for reducing the incidence of silent cerebral lesions with a new multi-electrode radiofrequency balloon catheter

Background

Silent cerebral lesions (SCL) often occur after invasive cardiac procedures. Reported SCL incidence with AF ablation varies (incidence, up to 50%), depending on technology used, procedural workflow, and detection method.

Objective

To evaluate the impact of ablation workflow modifications on SCL incidence following pulmonary vein isolation radiofrequency (RF) ablation with a novel multi-electrode RF balloon catheter in patients with symptomatic paroxysmal AF (PAF).

Methods

In the RADIANCE feasibility study of the balloon catheter, all enrolled patients who underwent ablation were screened for SCL using pre- and post-procedural diffusion-weighted MRI. Several modifications were made to the ablation workflow in a subsequent European registration study (SHINE) of the same catheter: eliminating dual transseptal access, using an over-the-wire mini lasso, continuously irrigating all side ports, bolus dosing with heparin before transseptal puncture, maintaining activated clotting time (ACT) at 350–400 sec, and setting a maximum temperature limit of 55°C (previously, 60–65°C). Interim data are presented for SHINE (data cutoff, 22 Oct 2018).

Results

In the neurological assessment evaluable (NAE) populations of RADIANCE (n=38) and SHINE (n=30), respectively, mean ages were 60.8±10.04 and 59.7±7.83 years, and 57.9% and 70.0% were male. One patient in each study had a history of TIAs. SCL incidences were 23.7% (10 lesions in 9 patients) in RADIANCE and 7.1% (2 lesions in 2 patients) in SHINE (excluding 1 SCL that occurred in a patient who failed to meet inclusion criteria [age>75] and 1 SCL that occurred after data cut-off). SHINE NAE enrollment has since completed with no further SCL occurrences. Overall, mean ACTs were 344.3±24.55 sec in RADIANCE and 381.6±73.31 sec in SHINE (p=0.01); in patients with SCL, mean ACTs were 349.3±25.65 and 417.8±87.33 sec, respectively.

Conclusion(s)

Modifications to the workflow led to a decrease in the SCL incidence for PAF ablation using the novel RF balloon catheter.

Acknowledgement/Funding

These studies were sponsored by Biosense Webster, Inc.

Ultrafiltration by Peritoneal Route in Refractory Chronic Congestive Cardiac Failure

Diuretics are the mainstay of treatment of refractory heart failure. There is a high incidence of dyselectrolytemia and suboptimal response due to diuretic resistance. Ultrafiltration by peritoneal route can be a safe and effective alternative. This study aims to study the ultrafiltration by peritoneal route in refractory heart failure patients with respect to change in functional status, renal parameters, left ventricular ejection fraction, number of days of hospitalization, and level of myocardial depressant factors. This was a prospective observational study conducted in Nephrology Department of tertiary care hospital. We studied patients with refractory heart failure who had persistent symptoms requiring frequent admissions despite optimal medical decongestion or had dyselectrolytemia with worsening renal parameters. The data were collected at baseline and then after 6 months of starting ultrafiltration. A total of 30 participants were studied. All the patients were in NYHA functional status Class IV before peritoneal ultrafiltration. There was a significant improvement in functional status and only 14 patients (46%) had Class III to Class IV status after application of ultrafiltration. (P < 0.001) There was a significant improvement in duration of hospital stay (75.8 ± 43.3 days to 7.8 ± 12.4, P > 0.001), serum creatinine (3.18 ± 0.98 to 2.16 ± 0.79 mg/dl, P < 0.001), and left ventricular ejection fraction [29.3 ± 7.4 (%) to 48.5 ± 11.8 (%), P < 0.0001] post ultrafiltration. There was also significant improvement in level of myocardial depressant factors (IL-1, IL-6, TNF alpha). Ultrafiltration by peritoneal route seems to be an effective alternative and should be offered to patients with chronic heart failure who are symptomatic despite maximal medical treatment.

Studies on a Miscible Polyimide Blend

Blends of polyimides XU-218 and PEI were investigated using differential scanning calorimetry, dynamic mechanical analysis, thermogravimetric analysis and adhesive bond testing. The thermal stability of the blends increased as the proportion of PEI increased while the α-relaxation of the blends occurred at a slower rate and was broader and more cooperative in some blends, compared with the pure polymers. Physical aging of the pure polymers and blends in the glass state revealed changes in relaxation rate and lost enthalpy that were also consistent with blends not behaving as simple mixtures. The dynamic mechanical and physical aging behaviour was attributed to an increase in density on blending which decreased the unoccupied volume and increased the constraints on molecular mobility, as well as to the presence of concentration fluctuations. The adhesive properties of the blends were also investigated and bond strength was found to vary with blend composition and test temperature.

Chronic vulval ulceration — another immune reconstitution inflammatory syndrome?

We describe a patient who developed intractable chronic vulval ulceration that we believe was related to immune reconstitution following treatment of HIV infection with highly active antiretroviral treatment (HAART). Immune reconstitution inflammatory syndrome should be considered in the differential diagnosis of unexplained vulval ulceration that arises after starting HAART.

ID: 72: INHIBITION OF NICOTINAMIDE PHOSPHORIBOSYLTRANSFERASE (NAMPT) ATTENUATES EXPERIMENTAL PULMONARY HYPERTENSION

Rationale

We have previously shown that Nampt, which regulates intracellular NAD levels and cellular redox state, regulates histone deacetylases and inhibits apoptosis, is significantly upregulated in patients with pulmonary arterial hypertension (PAH). The aims of this study were to determine (1) whether Nampt+/− mice are protected from hypoxia-mediated pulmonary hypertension (HPH), (2) whether pharmacological inhibition of Nampt could attenuate monocrotaline (MCT)-induced pulmonary hypertension (PH) in rats. In addition, we hypothesized that Nampt secreted from pulmonary artery endothelial cells (PAECs) or overexpressing Nampt in pulmonary artery smooth muscle cells (PASMCs) may promote PASMC proliferation via upregulation of calcium signaling pathway, which plays a role in cell proliferation and vascular constriction.

Methods

Nampt+/− mice and their WT siblings (male, 7-wk old) were exposed to a hypoxia chamber with 10% O2 for four weeks. Male Sprague-Dawley rats (n=6 per group) received one dose of MCT (60 mg/kg), IP. They were administrated with FK866 (an inhibitor of Nampt enzymatic activity) (2.5 mg/kg, IP, twice daily for 2wks) two weeks after MCT. Right ventricular systolic pressure (RVSP) was determined with a pressure transducer catheter. The right ventricle: left ventricle+septum (RV/LV+S) ratio was calculated. In a cell culture model, hPASMCs were stimulated with recombinant Nampt (25 mg/ml) for 6 hrs and 48 hrs. [Ca2+]cyt was measured in PASMC loaded with flura-2/AM (4mM) in a fluorescence microscope and cyclepiazonic acid (CPA, a specific Ca2+-ATPase inhibitor) was used to induce store-operated calcium entry (SOCE). In addition, BrdU assays were conducted to examine rNampt or overexpressing Nampt can promote PASMC proliferation or Nampt secreted from PAECs isolated from PAH patients stimulates more PASMC proliferation than from healthy controls.

Results

Administration of FK866 reversed established PH (RVSP [mm Hg] 19.77±0.80 [control] vs 51.24±4.35 [MCT] vs 34.45±3.49 [MCT+FK866], p<0.05 ) and RVH (0.25±0.0013 vs 0.60±0.019 vs 0.43±0.022, p<0.01). In PASMCs, short (6 hrs) and long (48 hrs) treatment with recombinant PBEF enhanced SOCE which is involved in sustained pulmonary vasoconstriction and PASMC proliferation. rNampt promotes PASMC proliferation in a dose dependent manner. PAECs from PAH patients secreted more Nampt which stimulates more PASMC proliferation compared to healthy controls. Overexpressed Nampt promotes PASMC proliferation. Inhibition of Nampt via FK866 attenuates rNampt-, Nampt overexpressed or PAEC-secreted Nampt – mediated PASMC proliferation.

Conclusion

Inhibition of Nampt attenuates hypoxia-mediated PH in mice or MCT-induced PH in rats. Nampt may play a role in vascular remodeling via regulation of calcium signaling pathway. These data suggest that Nampt inhibition could be a potential therapeutic target for PH.

Extended B cell phenotype in patients with myalgic encephalomyelitis/chronic fatigue syndrome: a cross-sectional study

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a heterogeneous condition of unknown aetiology characterized by multiple symptoms including fatigue, post-exertional malaise and cognitive impairment, lasting for at least 6 months. Recently, two clinical trials of B cell depletion therapy with rituximab (anti-CD20) reported convincing improvement in symptoms. A possible but undefined role for B cells has therefore been proposed. Studies of the relative percentages of B cell subsets in patients with ME/CFS have not revealed any reproducible differences from healthy controls (HC). In order to explore whether more subtle alterations in B cell subsets related to B cell differentiation exist in ME/CFS patients we used flow cytometry to immunophenotype CD19⁺ B cells. The panel utilized immunoglobulin (Ig)D, CD27 and CD38 (classical B cell subsets) together with additional markers. A total of 38 patients fulfilling Canadian, Centre for Disease Control and Fukuda ME/CFS criteria and 32 age- and sex-matched HC were included. We found no difference in percentages of classical subsets between ME/CFS patients and HC. However, we observed an increase in frequency (P < 0·01) and expression (MFI; P = 0·03) of CD24 on total B cells, confined to IgD⁺ subsets. Within memory subsets, a higher frequency of CD21⁺ CD38⁻ B cells (> 20%) was associated with the presence of ME/CFS [odds ratio: 3·47 (1·15-10·46); P = 0·03] compared with HC, and there was a negative correlation with disease duration. In conclusion, we identified possible changes in B cell phenotype in patients with ME/CFS. These may reflect altered B cell function and, if confirmed in other patient cohorts, could provide a platform for studies based on clinical course or responsiveness to rituximab therapy.