Evaluating the multivisceral involvement on adult-onset Still's disease to retrieve imaging-based differences in patients with and without macrophage activation syndrome: results from a single-centre observational study.

In this study, we aimed at describing the multivisceral involvement on adult-onset Still's disease (AOSD) to retrieve imaging-based differences in patients with and without macrophage activation syndrome (MAS). From our historical cohort, patients were assessed among those who underwent a total body CT scan. Clinical and CT scan characteristics of AOSD patients with and without MAS were compared. Out of 39 AOSD patients evaluated, 14 were complicated by MAS. These patients showed higher values of ferritin and systemic score. AOSD patients with MAS presented a higher prevalence of lung disease, hepatomegaly, splenomegaly, abdominal effusions, and lymph node enlargement than others without this complication. In addition, the presence of these manifestations significantly correlated with the systemic score, furtherly reinforcing its prognostic value. Due to the specific design of our study, our findings could be burdened by a selection bias since assessing those patients underwent a total body CT scan. Thus, these data should be prudently generalised suggesting the need of further studies to fully elucidate this issue. Our findings showed a higher prevalence of multiorgan involvement in AOSD patients with MAS, suggesting imaging-based differences, although other studies are needed to fully assess this issue. Pulmonary disease, hepatomegaly, splenomegaly, lymph node enlargement, and abdominal effusions were associated with a more aggressive subset of AOSD. Key Points •The importance of an accurate assessment AOSD multivisceral involvement is suggested since it is associated with life-threatening complications. •A higher prevalence of multiorgan involvement in AOSD patients with MAS could be recognised, than others without this complication, suggesting imaging-based differences. •AOSD multivisceral involvement may correlate with the systemic score, furtherly reinforcing its prognostic value.

Total metabolic lesion volume of lymph nodes measured by 18F-FDG PET/CT: a new predictor of macrophage activation syndrome in adult-onset Still's disease.

BACKGROUND: To investigate the potential utility of quantitative parameters obtained by 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in the assessment of disease severity and the occurrence of macrophage activation syndrome (MAS) in adult-onset Still's disease (AOSD). METHODS: Fifty-seven patients with AOSD who underwent pre-treatment 18F-FDG PET/CT were recruited in this study and compared with 60 age- and sex-matched healthy controls. Clinical features and laboratory data were recorded. The systemic score was assessed to determine the disease severity. The maximal standardized uptake value (SUVmax), metabolic lesion volume (MLV), and total lesion glycolysis (TLG) were used to evaluate the involved organs and tissues that abnormally accumulated 18F-FDG. Multivariate analysis was performed to identify the PET/CT-derived risk factors contributing to the AOSD-related MAS, and their diagnostic efficiency was evaluated. RESULTS: High 18F-FDG accumulation was observed in the bone marrow (SUVmax median, 5.10), spleen (SUVmax median, 3.70), and lymph nodes (LNs, SUVmax median, 5.55). The SUVmax of the bone marrow (rho = 0.376, p = 0.004), SUVmax of the spleen (rho = 0.450, p < 0.001), TLGtotal of LNs (rho = 0.386, p = 0.017), and MLVtotal of LNs (rho = 0.391, p = 0.015) were correlated with the systemic score. The SUVmax of the spleen (p = 0.017), TLGtotal of LNs (p = 0.045), and MLVtotal of LNs (p = 0.012) were higher in patients with MAS than in those without MAS. A MLVtotal of LNs > 62.2 (OR 27.375, p = 0.042) was an independent predictive factor for MAS with a sensitivity of 80.0% and a specificity of 93.9%. CONCLUSIONS: The glucose metabolic level of the spleen could be an effective and easy-to-use imaging indicator of disease severity, and MLVtotal of LNs > 62.2 was a strong predictor of MAS occurrence in patients with AOSD.

Lung involvement in macrophage activation syndrome and severe COVID-19: results from a cross-sectional study to assess clinical, laboratory and artificial intelligence-radiological differences.

OBJECTIVES: To evaluate the clinical pictures, laboratory tests and imaging of patients with lung involvement, either from severe COVID-19 or macrophage activation syndrome (MAS), in order to assess how similar these two diseases are. METHODS: The present work has been designed as a cross-sectional single-centre study to compare characteristics of patients with lung involvement either from MAS or severe COVID-19. Chest CT scans were assessed by using an artificial intelligence (AI)-based software. RESULTS: Ten patients with MAS and 47 patients with severe COVID-19 with lung involvement were assessed. Although all patients showed fever and dyspnoea, patients with MAS were characterised by thrombocytopaenia, whereas patients with severe COVID-19 were characterised by lymphopaenia and neutrophilia. Higher values of H-score characterised patients with MAS when compared with severe COVID-19. AI-reconstructed images of chest CT scan showed that apical, basal, peripheral and bilateral distributions of ground-glass opacities (GGOs), as well as apical consolidations, were more represented in severe COVID-19 than in MAS. C reactive protein directly correlated with GGOs extension in both diseases. Furthermore, lymphopaenia inversely correlated with GGOs extension in severe COVID-19. CONCLUSIONS: Our data could suggest laboratory and radiological differences between MAS and severe COVID-19, paving the way for further hypotheses to be investigated in future confirmatory studies.

The clinical utility of splenic fluorodeoxyglucose uptake for diagnosis and prognosis in patients with macrophage activation syndrome.

The aim of the study was to evaluate splenic glucose metabolism in macrophage activation syndrome (MAS), characterized by overwhelming systemic inflammation. Splenic F-fluorodeoxyglucose (FDG) uptake was compared in patients with MAS and sepsis using positron emission tomography/computed tomography (PET/CT).Clinical and FDG-PET/CT findings from patients with MAS and those with culture-proven sepsis were evaluated. The standardized uptake value (SUV) for the spleen and liver were measured. The maximum of the spleen to liver SUV ratio (SLRmax) was calculated as spleen SUVmax/liver SUVmean. The radiological splenic volume was also measured, and splenic metabolic volume (MV) was defined as the total splenic volume with an SLRmean > 1.14. The association between clinical features, laboratory variables, and SLRmax was analyzed.The median SLRmax and splenic MV were significantly higher in patients with MAS (n = 38) than they were in those with sepsis (n = 15) (SLRmax: 1.51 vs 1.09, P = .001; MV: 346.0 vs 154.0, P = .015). Multivariate analyses revealed that SLRmax > 1.31 was useful for discriminating between MAS and sepsis. SLRmax positively correlated with ferritin and lactate dehydrogenase level in MAS. Furthermore, MAS patients with high splenic FDG uptake (SLRmax > 1.72) had higher in-hospital mortality compared to those with moderate to low splenic FDG uptake (P = .013).This study was the first to demonstrate that splenic FDG uptake is significantly elevated in patients with MAS compared to those with sepsis. This may be useful to differentiate between MAS and sepsis, and to predict poor prognosis in patients with MAS.

FDG-PET in macrophage activation syndrome associated with systemic juvenile idiopathic arthritis.

We herein describe a case of systemic juvenile idiopathic arthritis (s-JIA)-associated macrophage activation syndrome (MAS) in which the 18F fluorodeoxyglucose positron emission tomography (18F FDG-PET) findings were characteristic. The pattern of greater 18F FDG accumulation into the spleen compared with the liver was more remarkable in this patient compared with s-JIA. This pattern, however, was also observed in cases of acute leukemia. In the present patient, serum interleukin (IL)-18 was extremely elevated (255 000 pg/mL), whereas in leukemia patients it is mildly elevated (360-1480 pg/mL). 18F FDG-PET might be a useful indicator of s-JIA and MAS in patients with fever of unknown origin. The pattern of 18F FDG accumulation, however, can also be observed in acute leukemia. The combination of 18F FDG-PET and serum IL-18 might be useful for the diagnosis of s-JIA and MAS.

Macrophage Activation Syndrome.

Macrophage activation syndrome (MAS) is a potentially life-threatening complication of rheumatic diseases such as systemic juvenile idiopathic arthritis (sJIA) and systemic lupus erythematosus. It is often considered a type of secondary hemophagocytic lymphohistiocytosis (HLH) and results from over-activation of T lymphocytes and macrophages leading to a "cytokine storm". Characteristic features are persistent fever, lymphadenopathy, hepatosplenomegaly, cytopenias (anemia, leucopenia, thrombocytopenia), raised C-reactive protein, falling erythrocyte sedimentation rate, hypofibrinogenemia, transaminitis, hypertriglyceridemia and extreme hyperferritinemia often associated with multi-organ impairment. Key to its management is early recognition of MAS which may be difficult due to similarity to systemic sepsis or flares of the underlying rheumatic disease. To aid with this process, criteria for the diagnosis of MAS in patients with sJIA derived by international consensus have been published. Although bone marrow biopsy showing hemophagocytosis is strongly supportive it is not essential for diagnosis. Together with appropriate supportive care, first-line treatment is high-dose intravenous corticosteroids with cyclosporin or intravenous immunoglobulin (IVIg) added if there is not initial response. Although etoposide is used by hematologists in treatment of HLH, there are concerns regarding organ toxicity and bone marrow suppression which weigh against its use in initial management of MAS. With increasing understanding of the pathogenesis of MAS, use of drugs targeting specific cytokines has been reported in case series. The relatively rapid effectiveness of anakinra, a recombinant IL-1 receptor antagonist, has been documented. Further studies of this and other biologic agents are required to identify the most effective and safest treatment option for refractory MAS.

Macrophage activation syndrome or septic arthritis: a case of mistaken identity.

We present an interesting case of macrophage activation syndrome in a 2-year-old, with no previous rheumatological diagnoses, incorrectly diagnosed with septic arthritis, to highlight the diagnostic difficulties, especially in small hospital units. We aim to present the similarities between the two conditions and to summarize the clinical, radiological and epidemiological features of macrophage activation syndrome, an underdiagnosed condition. A review of the current literature was performed, and a diagnostic algorithm was created. No current set treatment regimen exists, but current recommendations have been included. We have demonstrated the pitfalls in diagnosis and the importance of immediate treatment in optimizing prognosis.