Significance of F-18 FDG PET/MRI in the search for the etiology of inflammation of unclear origin and fever of unknown origin.

PURPOSE: To evaluate the contribution of F-18 FDG-PET/MRI in the search for the etiology of the inflammation of unknown origin (IUO) and fever of unknown origin (FUO). MATERIAL AND METHODS: The study included 104 patients who underwent F-18 FDG-PET/MRI for IUO or FUO. The sensitivity, specificity, predictive values of the PET/MRI findings in relation to the final diagnosis of IUO/FUO were evaluated. A five-point Likert scale was used to semiquantitatively assess the probability of the cause of IUO/FUO based on PET/MRI finding. Furthermore, clinical (fever, arthralgia, weight loss, night sweats, age) and laboratory (C-reactive protein, leukocytes) parameters were monitored and compared with the true positivity rate of PET/MRI. RESULTS: In patients with definitively identified etiology of FUO and IUO, FDG-PET/MRI achieved a sensitivity of 96 %, specificity of 82 %, and positive and negative predictive values of 92 and 90 %. The cause of the IUO was determined in 71 patients (68.3 %). In 33 (31.7 %) patients, the etiology of IUO/FUO remained unknown, while in 25 (75.8 %) of them the symptoms resolved spontaneously and in 8 (24.2 %) patients they persisted without explanation even after 12 months of the follow-up. The most significant parameter in relation to subsequent PET/MRI finding was increased level of CRP, which was present in 96 % of true positive PET/MRI and normal CRP level was present in 56 % of true negative PET/MRI. CONCLUSION: Based on this study, FDG-PET/MRI is a suitable alternative for the investigation of IUO/FUO, this imaging technique has a very high sensitivity and negative predictive value.

Coexistence of FDG-Avid and FDG-Negative Aneurysms in a Patient With Fever of Unknown Origin.

ABSTRACT: A 68-year-old man with intermittent fever of unknown origin for 5 months underwent 18F-FDG PET/CT to detect causative lesion. An 18F-FDG-avid lesion was revealed in the left pelvic iliac vessel region and was highly suggestive of malignancy. One and a half months later, a giant left internal iliac artery aneurysm was identified by CT angiography, corresponding to the 18F-FDG-avid lesion. Combined with elevated inflammatory markers, he was finally diagnosed as having inflammatory internal iliac artery aneurysm. An abdominal aortic aneurysm with low 18F-FDG uptake was also identified.

Risk factors that are associated with adrenal insufficiency among patients with fever of unknown origin.

BACKGROUND: Adrenal insufficiency is one of the causes of fever of unknown origin (FUO). The purpose of this study is to find out risk factors that are associated with adrenal insufficiency in FUO patients. METHODS: This study was conducted retrospectively in a tertiary hospital with 846 beds in South Korea. All adult inpatients (age ≥19 years) who have requested a consult with the department of infectious disease for FUO between 1 July 20191 July 2019 and 30 June 202030 June 2020 were included in the study. Among them, those who underwent an adrenocorticotropic hormone (ACTH) stimulation test and had a fever of 37.8°C or higher within 48 hours of the ACTH stimulation test were finally included in the study subjects. RESULTS: A total of 202 FUO patients were enrolled and 61 (30.1%) were finally diagnosed with adrenal insufficiency. In a multivariate analysis, use of immunosuppressant within 3 months (OR 6.06, 95% CI 1.82-20.13, P = 0.003), use of corticosteroid within 3 months (OR 8.23, 95% CI 1.35-50.17, P = 0.022), sodium ≥ 136.7 (OR 3.43, 95% CI 1.49-7.88, P = 0.004), and calcium ≥ 8.4 (OR 0.31, 95% CI 0.14-0.71, P = 0.005) were proven to be factors associated with adrenal insufficiency in FUO patients. CONCLUSION: In conclusion, 30.1% of FUO patients were diagnosed with adrenal insufficiency. The risk factors that are associated with adrenal insufficiency in FUO patients were immunosuppressive prescription or systemic steroid prescription within 3 months, or with sodium ≥ 136.7 or calcium < 8.4.

Development of a risk prediction model for bloodstream infection in patients with fever of unknown origin.

BACKGROUND: Bloodstream infection (BSI) is a significant cause of mortality among patients with fever of unknown origin (FUO). Inappropriate empiric antimicrobial therapy increases difficulty in BSI diagnosis and treatment. Knowing the risk of BSI at early stage may help improve clinical outcomes and reduce antibiotic overuse. METHODS: We constructed a multivariate prediction model based on clinical features and serum inflammatory markers using a cohort of FUO patients over a 5-year period by Least Absolute Shrinkage and Selection Operator (LASSO) and logistic regression. RESULTS: Among 712 FUO patients, BSI was confirmed in 55 patients. Five independent predictors available within 24 h after admission for BSI were identified: presence of diabetes mellitus, chills, C-reactive protein level of 50-100 mg/L, procalcitonin > 0.3 ng/mL, neutrophil percentage > 75%. A predictive score incorporating these 5 variables has adequate concordance with an area under the curve of 0.85. The model showed low positive predictive value (22.6%), but excellent negative predictive value (97.4%) for predicting the risk of BSI. The risk of BSI reduced to 2.0% in FUO patients if score < 1.5. CONCLUSIONS: A simple tool based on 5 variables is useful for timely ruling out the individuals at low risk of BSI in FUO population.

Clinical Features of Spontaneous Remission in the Classic Fever of Unknown Origin: A Retrospective Study.

Objective To summarize the clinical features of spontaneous remission in classic fever of unknown origin (FUO). Methods Medical records of 121 patients diagnosed with FUO at admission in Peking Union Medical College Hospital between January 2018 and June 2018 were reviewed retrospectively. Patients who were discharged without etiological diagnoses were followed for 2 years. The clinical features and outcomes of these patients were summarized. Multivariate logistic regression was used to analyze related factors of spontaneous remission of FUO. Results After excluding 2 patients who lost to follow-up, the etiology of 119 FUO patients were as follows: infectious diseases in 30 (25.2%) cases, connective tissue diseases in 28 (23.5%) cases, tumor diseases in 8 (6.7%) cases, other diseases in 6 (5.0%) cases, and unknown diagnoses in 47 (39.5%) cases. Totally, 41 patients experienced spontaneous remission of fever (the median time from onset to remission was 9 weeks, ranging from 4 to 39 weeks). In patients with spontaneous remission in FUO, lymphadenopathy was less common clinical manifestation, the levels of inflammatory markers including leukocyte count, neutrophil count, neutrophil ratio, C-reactive protein, and ferritin were lower, and the proportion of CD8 positive T lymphocytes expressing CD38 was lower. Multivariate logistic regression analysis of factors with a P-value < 0.05 in univariate analysis shown that white blood cell count (OR: 0.545, 95%CI: 0.306-0.971, P = 0.039), neutrophil count (OR: 2.074, 95%CI: 1.004-4.284, P = 0.049), and proportion of neutrophils (OR: 0.928, 95%CI: 0.871-0.990, P = 0.022) were independent significant factors associated with spontaneous remission in FUO. Conclusions This study suggested that most patients discharged with undiagnosed classic FUO would remit spontaneously. Thus, for patients with stable clinical conditions, follow-up and observation could be the best choice. Patients with lower level of some inflammatory factors may have a high likelihood of spontaneous remission in classic FUO.

Acute Fever of Unknown Origin: A Presentation of West Nile Encephalitis.

INTRODUCTION: West Nile virus is an asymptomatic infection in most cases, but it can present with a rare complication of deadly neuroinvasive disease. CASE PRESENTATION: A 81-year-old White man presented with altered mental status and fever of unknown origin. After extensive workup, he was diagnosed with West Nile encephalitis based on positive serology, lumbar puncture, and clinical presentation. DISCUSSION: West Nile virus is a mosquito-borne RNA arbovirus that, in rare cases, can lead to encephalitis, which is a challenging diagnosis. There is no current treatment; however, a 5-day course of intravenous immunoglobulin seemed to show acute clinical improvement in both mentation and magnetic resonance imaging of the head and no long-term effects. CONCLUSION: We report this case to increase awareness among clinicians to include West Nile virus in the differential diagnosis of encephalitis with fever of unknown origin, particularly in endemic areas.

Rheumatic disorders among patients with fever of unknown origin: A systematic review and meta-analysis.

OBJECTIVES: To conduct a systematic literature review and meta-analysis to estimate the proportion of fever of unknown origin (FUO) and inflammation of unknown origin (IUO) cases that are due to rheumatic disorders and the relative frequency of specific entities associated with FUO/IUO. METHODS: We searched PubMed and EMBASE between January 1, 2002, and December 31, 2021, for studies with ≥50 patients reporting on causes of FUO/IUO. The primary outcome was the proportion of FUO/IUO patients with rheumatic disease. Secondary outcomes include the association between study and patient characteristics and the proportion of rheumatic disease in addition to the relative frequency of rheumatic disorders within this group. Proportion estimates were calculated using random-effects models. RESULTS: The included studies represented 16884 patients with FUO/IUO. Rheumatic disease explained 22.2% (95%CI 19.6 - 25.0%) of cases. Adult-onset Still's disease (22.8% [95%CI 18.4-27.9%]), giant cell arteritis (11.4% [95%CI 8.0-16.3%]), and systemic lupus erythematosus (11.1% [95%CI 9.0-13.8%]) were the most frequent disorders. The proportion of rheumatic disorders was significantly higher in high-income countries (25.9% [95%CI 21.5 - 30.8%]) versus middle-income countries (19.5% [95%CI 16.7 - 22.7%]) and in prospective studies (27.0% [95%CI 21.9-32.8%]) versus retrospective studies (20.6% [95%CI 18.1-24.0%]). Multivariable meta-regression analysis demonstrated that rheumatic disease was associated with the fever duration (0.011 [95%CI 0.003-0.021]; P=0.01) and with the fraction of patients with IUO (1.05 [95%CI 0.41-1.68]; P=0.002). CONCLUSION: Rheumatic disorders are a common cause of FUO/IUO. The care of patients with FUO/IUO should involve physicians who are familiar with the diagnostic workup of rheumatic disease.

Safety and risk of febrile recurrence after early antibiotic discontinuation in high-risk neutropenic patients with haematological malignancies: a multicentre observational study.

BACKGROUND: Early antibiotic discontinuation according to the Fourth European Conference on Infections in Leukaemia (ECIL-4) recommendations is not systematically applied in high-risk neutropenic patients with haematological malignancies. METHODS: A retrospective multicentre observational study was conducted over 2 years to evaluate the safety of early antibiotic discontinuation for fever of unknown origin (FUO) during neutropenia after induction chemotherapy or HSCT, in comparison with a historical cohort. We used Cox proportional hazards models, censored on neutropenia resolution, to analyse factors associated with febrile recurrence. RESULTS: Among 147 included patients in the ECIL-4 cohort, mainly diagnosed with acute leukaemia (n = 104, 71%), antibiotics were discontinued during 170 post-chemotherapy neutropenic episodes. In comparison with the historical cohort of 178 episodes of neutropenia without antibiotic discontinuation, no significant differences were observed regarding febrile recurrences [71.2% (121/170) versus 71.3% (127/178), P = 0.97], admission in ICUs [6.5% (11/170) versus 11.2% (20/178), P = 0.17], septic shock [0.6% (1/170) versus 3.9% (7/178), P = 0.07] and 30 day mortality [1.4% (2/147) versus 2.7% (4/150), P = 0.084]. In the ECIL-4 cohort, the rate of bacteraemia in case of febrile recurrence was higher [27.1% (46/170) versus 11.8% (21/178), P < 0.01] and antibiotic consumption was significantly lower (15.5 versus 19.9 days, P < 0.001). After early antibiotic discontinuation according to ECIL-4 recommendations, enterocolitis was associated with febrile recurrence [HR = 2.31 (95% CI = 1.4-3.8), P < 0.001] and stage III-IV oral mucositis with bacteraemia [HR = 2.26 (95% CI = 1.22-4.2), P = 0.01]. CONCLUSIONS: After an FUO episode in high-risk neutropenia, compliance with ECIL-4 recommendations for early antibiotic discontinuation appears to be safe and mucosal damage was associated with febrile recurrence and bacteraemia. Prospective interventional studies are warranted to assess this strategy in high-risk neutropenic patients.

[Case report: persistent fever after SARS-CoV-2 infection]. / Fallbericht: Persistierendes Fieber nach SARS-CoV-2-Infektion.

A 44-year-old man had persistent fever following a severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection. Because of progressive sinus tachycardia, thyroid hormones were measured which showed hyperthyroidism. Thyroid sonography revealed enlargement of the thyroid gland with hypoechoic areas with blurred margins. We diagnosed subacute granulomatous thyroiditis associated with SARS-CoV­2 infection and initiated therapy with prednisolone. This therapy resulted in rapid improvement of the patient's clinical condition and complete remission after three months.

Fever of unknown origin: evaluation of 110 classical and HIV-associated cases in the last decade.

BACKGROUND: Fever is one of the critical symptoms of collagen vascular diseases, malignancies, and infectious diseases. Patients with a fever of unknown origin (FUO) were evaluated to determine the etiology. METHODS: In this study, 110 cases with FUO who were admitted to two hospitals with a total of 800 beds, in which 5000 daily outpatient patients were admitted between 2006 and 2016 have been evaluated retrospectively. Anamnesis and the findings were obtained from hospital records. Patients with a temperature higher than 38.3°C and lasting three weeks or longer without diagnosis despite one week of investigation in the hospital were included as FUO cases in this study. Nosocomial and neutropenic cases were excluded from the present study. RESULTS: Fifty-seven patients were male (52%), and the mean age was 40.2 ± 17.2. The distribution of the classic and HIV-associated cases was 85 (77.3%) and 18 (16.4%). Tuberculosis (TB) was the most frequent disease in both groups. The etiology was infectious in 68.2%, autoimmune in 14.5%, and neoplastic in 5.4%. There was no case of collagen vascular disease in the HIV-associated FUO group. CONCLUSION: As a result of our study, infectious diseases and TB were still the leading factors that caused FUO. TB has been notably found higher in the HIV-associated group than the classic group. FUO is usually either a rare cause or an unusual clinical presentation of a well-known infectious disease in Turkey. Therefore, it should be noted that various manifestations of extra-pulmonary tuberculosis may be considered a FUO case.

Second-trimester miscarriage caused by recurrent Klebsiella pneumoniae infection: a case report.

BACKGROUND: Klebsiella pneumoniae (K. pneumoniae) can cause hospital- and community-acquired pneumonia, and urinary tract, wound, and blood infections. As there are few reports on K. pneumoniae infections in pregnancy and no treatment guidelines, diagnosis and treatment are difficult. The diagnosis and treatment require a bacterial culture to confirm the diagnosis. Therefore, the condition is often exacerbated due to a lack of timely medication. CASE DESCRIPTION: We report a case of a pregnant woman with recurrent K. pneumoniae infection during pregnancy. The 40-year-old woman was admitted to hospital at 14 weeks gestation due to fever of unknown origin. She was treated with empiric antibiotics, and her fever resolved within 1 day. A blood culture showed K. pneumoniae infection. She was discharged after 11 days of treatment. However, 10 days later, she was re-hospitalized due to fever, and treated with cefoperazone sodium and sulbactam sodium. Her fever resolved within 1 day. A blood culture again showed K. pneumoniae infection. On day 5, she experienced chills and a miscarriage. Cervical secretions showed K. pneumoniae, and a placental examination revealed chorioamnionitis. The treatment was changed to meropenem, and the patient recovered within 2 weeks. CONCLUSIONS: When a fever of unknown origin occurs during pregnancy, one should be wary of K. pneumoniae recurrence or secondary infection, and use sensitive antibiotics early. When K. pneumoniae is cultivated, the course of treatment must be sufficient, and the source of infection must be actively searched to prevent secondary infections, such as kidney cysts, liver cysts, lung cysts, and community infections. Finding the cause and taking appropriate treatment can prevent the occurrence of adverse pregnancy and childbirth history.

Fever of Unknown Origin - infected Fistula-in-Ano as the focus on 18F-FDG PET-CT.

Fever of Unknown Origin (FUO) is a vexing clinical problem. Diagnosis of aetiology is essential for definitive management. A wide array of infective, inflammatory, malignant and miscellaneous pathologies can cause FUO. Hybrid imaging with 18F-Fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) is now an integral part of FUO management because of its ability to demonstrate the cause in a large proportion of cases. The authors present the case of a 42-year-old male, where an infected fistula-in-ano was detected as the cause of FUO on 18F-FDG PET-CT.

Rare Case of Testicular Sarcoidosis Detected on FDG PET/CT in a Patient With PUO.

Genitourinary sarcoidosis is an uncommon entity, and testicular sarcoidosis is even rarer. We present a case of 66-year-old man who presented to our hospital as PUO (pyrexia of unknown origin) and later diagnosed as testicular sarcoidosis with the help of FDG PET/CT.

Enterovirus, parechovirus, adenovirus and herpes virus type 6 viraemia in fever without source.

OBJECTIVES: To evaluate the potential associations between fever without a source (FWS) in children and detection of human enterovirus (HEV), human parechovirus (HPeV), adenovirus (AdV) and human herpesvirus type 6 (HHV-6) in the plasma; and to assess whether the detection of viruses in the plasma is associated with a reduced risk of serious bacterial infection (SBI) and antibiotic use. DESIGN AND SETTING: Between November 2015 and December 2017, this prospective, single-centre, diagnostic study tested the plasma of children <3 years old with FWS. Real-time (reverse-transcription) PCR for HEV, HPeV, AdV and HHV-6 was used in addition to the standardised institutional work-up. A control cohort was also tested for the presence of viruses in their blood. RESULTS: HEV, HPeV, AdV and HHV-6 were tested for in the plasma of 135 patients of median age 2.4 months old. At least one virus was detected in 47 of 135 (34.8%): HEV in 14.1%, HHV-6 in 11.1%, HPeV in 5.9% and AdV in 5.2%. There was no difference in antibiotic use between patients with or without virus detected, despite a relative risk of 0.2 for an SBI among patients with viraemia. Controls were less frequently viraemic than children with FWS (6.0% vs 34.8%; p<0.001). CONCLUSIONS: HEV, HPeV, AdV and HHV-6 are frequently detected in the plasma of children with FWS. Antibiotic use was similar between viraemic and non-viraemic patients despite a lower risk of SBI among patients with viraemia. Point-of-care viral PCR testing of plasma might reduce antibiotic use and possibly investigations and admission rates in patients with FWS. TRIAL REGISTRATION NUMBER: NCT03224026.

Connecting the Dots From Fever of Unknown Origin to Myelodysplastic Syndrome: GATA2 Haploinsufficiency.

Leukemia-predisposing conditions, such as GATA2 haploinsufficiency, are known for their high penetrance and expressivity profiles. These disorders pose a difficult diagnostic challenge to even the most experienced clinician when they first present. We describe the case of a 17-year-old male presenting with features of nontuberculous mycobacterial infection, pulmonary fibrinoid granulomatous vasculitis, and myelodysplasia in the setting of a pathogenic GATA2 frameshift mutation confirmed by next-generation sequencing. The broad differential for GATA2 haploinsufficiency requires prompt recognition of key clinical features and laboratory abnormalities towards directing diagnosis and guiding appropriate and perhaps life-saving therapy.

Factors associated with treatment type of non-malarial febrile illnesses in under-fives at Kenyatta National Hospital in Nairobi, Kenya.

BACKGROUND: Non-malarial febrile illnesses comprise of almost half of all fever presenting morbidities, among under-five children in sub-Saharan Africa. Studies have reported cases of prescription of antimalarial medications to these febrile under-fives who were negative for malaria. The treatment of these children with antimalarial medications increases incidences of antimalarial drug resistance as well as further morbidities and mortalities, due to failure to treat the actual underlying causes of fever. AIM: To identify clinical and demographic factors associated with treatment type (malarial/non-malarial) of non-malarial febrile illnesses (NMFI) in children aged ≤5 at the Kenyatta National Hospital in Nairobi, Kenya. METHODS: A positivist epistemological approach, cross sectional descriptive study design was used. A structured questionnaire was used on a sample of 341 medical records of children aged ≤5 years to extract data on clinical examinations (recorded as yes or no), diagnostic test results, and demographic data on the child's sex and age. Descriptive and inferential analysis was applied to the data. RESULTS: Prescription of antimalarial drugs despite negative microscopy results was found in 44 (12.9%) of the children, with mortality reported in 48 (14.1%). Assessment of respiratory distress was 0.13 (0.03,0.58) times associated with less likelihood of prescribing an antimalarial in those with a negative microscopy. A male patient was 0.21 (0.05,0.89) times less likely to receive an intravenous antimalarial after a negative microscopy. Patients aged ˂1 with a negative microscopy result were more likely to receive an antimalarial than older children. CONCLUSION: There is a need to eliminate incorrect treatment of NMFI with antimalarial medication, while ensuring correct diagnosis and treatment of the specific illness occurs. This requires strengthening and adherence to diagnostic and treatment guidelines of febrile illnesses in under-fives, consequently reducing morbidities and mortalities associated with inadequate management of NMFIs.

Inflammatory Activity of Tumoral Calcinosis in a Patient With Fever of Unknown Origin.

Unexpected inflammatory activity of tumoral calcinosis periarticular to the shoulders and hips in a man with recurrent fever of unknown origin and dialysis-dependent kidney insufficiency was revealed by FDG PET/CT. In absence of other pathologies, the calcinosis was deemed to be the cause of the fever. An infectious or malignant disease could be ruled out, so further therapeutic steps were enabled.

Diagnóstico de vasculitis en estudio 18F-FDG PET/TC en paciente con fiebre de origen desconocido / Diagnosis of vasculitis with 18F-FDG PET/CT study in patient with fever of unknown origin

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Giant cell arteritis presenting as isolated inflammatory response and/or fever of unknown origin: a case-control study.

The objective of this study was to determine the proportion and characteristics of patients with giant cell arteritis (GCA) who present with isolated inflammatory response and/or fever of unknown origin (IFUO). Using a cohort of 693 consecutive patients in two centers with evidence of GCA on biopsy and/or imaging, we compared the characteristics and outcomes of patients with IFUO at diagnosis to a control group made up of the remaining patients with GCA. Sixty-one (9%) patients initially presented with IFUO. GCA diagnosis was proven by biopsy in 50 (82%) patients and/or imaging in 23 out of 39 (59%) patients who underwent large-vessel imaging. At diagnosis, patients with IFUO were younger (p = 0.008), had longer time to diagnosis (p = 0.001), and showed more intense inflammatory response, i.e., had higher levels of C-reactive protein (p = 0.02) and lower hemoglobin levels (p = 0.0001) than control patients. However, the therapeutic regimen did not differ between the two groups. Similarly, during a median follow-up period of 50 [0-279] months, the total rate of cardiovascular events, including ischemic cranial complications and overall outcomes, including relapse, glucocorticoids-dependence and death rates did not differ between the two groups. Five (16%) patients with initial IFUO exhibited cranial symptoms at relapse. Giant cell arteritis presenting with isolated inflammatory response and/or fever of unknown origin is a well-defined demographic and clinical pattern affecting nearly 10% of patients. This clinical form is not associated with a particular prognosis but remains a challenging diagnosis.