The first part of the guidelines and recommendations for musculoskeletal ultrasound, produced under the auspices of the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB), provides information about the use of musculoskeletal ultrasound for assessing extraarticular structures (muscles, tendons, entheses, ligaments, bones, bursae, fasciae, nerves, skin, subcutaneous tissues, and nails) and their pathologies. Clinical applications, practical points, limitations, and artifacts are described and discussed for every structure. After an extensive literature review, the recommendations have been developed according to the Oxford Centre for Evidence-based Medicine and GRADE criteria and the consensus level was established through a Delphi process. The document is intended to guide clinical users in their daily practice.

The second part of the Guidelines and Recommendations for Musculoskeletal Ultrasound (MSUS), produced under the auspices of EFSUMB, following the same methodology as for Part 1, provides information and recommendations on the use of this imaging modality for joint pathology, pediatric applications, and musculoskeletal ultrasound-guided procedures. Clinical application, practical points, limitations, and artifacts are described and discussed for every joint or procedure. The document is intended to guide clinical users in their daily practice.

Distinguishing tuberculous spondylodiscitis (TS) from pyogenic spondylodiscitis (PS) on imaging remains clinically important because the two entities differ in antimicrobial strategy, surgical timing, and the urgency of microbiological workup, yet no single imaging sign is pathognomonic for either diagnosis. When tissue confirmation is delayed, imaging becomes the primary tool that shifts pre-test probability and guides biopsy strategy—a role that is particularly critical in culture-negative disease, in antibiotic-exposed patients, and in settings with limited access to rapid mycobacterial diagnostics. This narrative review maps the imaging evidence most useful for routine TS-versus-PS differentiation, synthesizes recent prediction models and quantitative tools, and evaluates the adjunctive role of ¹⁸F-FDG PET/CT in biopsy-oriented decision-making. PubMed/MEDLINE was searched from inception to 31 March 2026 using pre-specified search terms across three concept blocks. This was a narrative review without formal pooling of quantitative estimates or prospective protocol registration. A secondary Scopus search identified no additional eligible records. Priority was given to comparative TS-versus-PS imaging cohorts, meta-analyses of MRI and CT features, prediction-model studies, and the recent radiomics and PET/CT literature; radiomics and deep-learning studies are appraised as a distinct evidence tier given their retrospective single-center derivation and predominantly internal-only validation. In total, 14 comparative TS-versus-PS imaging cohorts, three meta-analyses, and 14 prediction-model, quantitative-scoring, radiomics, or deep-learning studies formed the core evidence base. MRI yields the greatest differentiating information and is the recommended first-line modality. Features favoring TS include thoracic predominance, multilevel or non-contiguous involvement, relative early disc preservation, subligamentous spread, intraosseous abscesses, thin-walled paravertebral collections, and severe vertebral collapse with kyphotic deformity. Features favoring PS include lumbar predominance, early disc-endplate destruction, homogeneous inflammatory enhancement, facet-joint arthritis, and epidural phlegmon. CT adds osseous detail—including sequestra, subligamentous bone erosion, and paravertebral calcification—and remains the primary guidance modality for biopsy. Recent prediction models combining imaging and laboratory variables have shown high discriminative performance in derivation cohorts; however, most remain internally validated and locally calibrated. Pending external validation, none should be considered ready for unmodified clinical adoption, and they should therefore be used as probability modifiers rather than stand-alone diagnostic rules. ¹⁸F-FDG PET/CT is complementary rather than primary and is most useful when MRI is contraindicated or equivocal, in hardware-associated infection, and for whole-body staging in suspected disseminated tuberculosis. Non-infectious mimics and alternative infectious diagnoses should be considered when the imaging pattern is internally inconsistent or when standard cultures remain negative. Imaging findings should refine etiological probability and guide biopsy strategy, but should not replace tissue confirmation when tissue is feasible. Non-imaging evidence complementing this review is addressed in the companion manuscript, Part I.

Distinguishing tuberculous spondylodiscitis (TS) from pyogenic spondylodiscitis (PS) remains difficult when presentation is non-specific, blood cultures are negative, or initial biopsy is non-diagnostic. The two entities differ substantially in antimicrobial strategies, resistance testing requirements, public health interventions, and surgical thresholds, yet diagnostic delay is associated with neurological deficits, spinal instability, and permanent deformity. This narrative review maps the non-imaging evidence most useful for frontline differentiation between TS and PS across five domains: epidemiology and risk stratification, clinical presentation, laboratory markers, tissue acquisition and histopathology, and molecular diagnostics. PubMed/MEDLINE was searched from inception to 31 March 2026 using pre-specified Boolean search terms; a secondary Scopus search identified no additional eligible records. Following screening, approximately 90 records were included in this synthesis. Priority was given to comparative TS-versus-PS cohorts, biopsy-yield and culture-negative studies, pathology series, pediatric data, and recent molecular diagnostics literature. Epidemiological TB (tuberculosis) risk, longer symptom duration, constitutional symptoms, deformity, and a less intense acute-phase response increase the probability of TS, whereas healthcare exposure, bacteraemia, recent spinal procedures, and brisk neutrophilic inflammation favor PS. In stable patients, the highest-yield strategy is early blood cultures followed by image-guided biopsy with parallel tissue allocation for bacterial culture, mycobacterial studies, histopathology, and selected molecular assays. No single laboratory marker reliably distinguishes TS from PS without tissue confirmation. Per a 2023 systematic review and meta-analysis, image-guided percutaneous biopsy achieves microbiological confirmation in approximately one-third of cases. Histopathology demonstrating caseating granulomatous inflammation supports TS, although a substantial minority of confirmed cases lack classic features. Supported by cohort prospective data, Xpert MTB/RIF Ultra has the clearest first-line molecular role when TS is plausible and should be requested at the time of first biopsy rather than reserved for salvage testing; broader or targeted next-generation sequencing is best reserved for selected unresolved cases. Imaging differentiation is addressed in the companion manuscript, Part II.

Background Anti-synthetase syndrome (ASS) is a rare auto-immune condition that combines autoantibodies and specifics clinical manifestations, including myositis, interstitial lung disease (ILD), polyarthritis, mechanic’s hands, Raynaud’s phenomenon, and unexplained fever. The hallmark of this syndrome is the presence of anti-aminoacyl-tRNA-synthetase (ARS) antibodies. Several anti-ARS antibodies have been described, anti-Jo1 being the most common, followed by anti-PL7, anti-PL12, anti-OJ, anti-EJ, anti-KS, anti-YRS, and anti-Zo. According to a recent epidemiological survey, the rising number of patients with autoimmune diseases, including idiopathic inflammatory myopathies (IIM) coincides with the COVID-19 pandemic. Objectives To evaluate the clinical characteristics of ASS patients with different anti-ARS antibodies from a tertiary rheumatology center. Methods We conducted a retrospective, single-centered study on consecutive patients diagnosed with ASS from 1 January 2015 to 31 December 2022. Clinical and serologic data were obtained by medical records review from hospital database. Myositis-specific antibodies (MSA) and myositis-associated antibodies (MAA) were tested using commercial ELISA kits. We included all patients fulfilling Connor’s criteria for ASS. Results Sixty-one patients (44 females) with mean age 54.4 (13.8) years were included. The most frequently reported clinical manifestation was arthralgia (68.8%), followed by Raynaud’s phenomenon (67.2%), ILD (65.6%), myositis (46%), mechanic’s hands (44.3%), arthritis (39.3%), and fever (18.0%). The typical triad for ASS, including myositis, arthritis and ILD was present in 17 patients. Twenty-eight (45.9%) patients were PL7+, 21 (34.4%) were Jo1+, 3 (4.9%) were PL12+, and 2 (3.2%) were OJ+. Seven patients were positive for more than two anti-ARS antibodies. The most frequently found MAA was anti-Ro52 (n=23, 37.7%). Of the 61 patients included, 41 (67.2%) patients were diagnosed in the last 3 years (COVID-19 pandemic). The most frequently detected MSA in ASS patients diagnosed during COVID-19 pandemic was anti-PL7 (25/28), while anti-Jo1 was the most common MSA in ASS patients diagnosed before 2020 (p<0.05) (Fig 1). The anti-Jo1+ patients were younger, have significantly more frequent muscle involvement and significantly higher levels of CK than anti-PL7+ patients (p<0.05). The co-occurance of anti-Ro52 antibodies was more frequently observed in anti-Jo1+ patients (n=11, 52.4%) than in anti-PL7+ patients (n=6, 21.4%) (p0.05). Conclusion ASS patients have heterogenous manifestations, and different types of anti-ARS antibodies are associated to distinct clinical and immunological features. The COVID-19 pandemic led to increase prevalence of ASS cases and to a remarkable shift in the anti-ARS antibodies profile, with increased frequency of anti-PL7 antibodies. Further studies are needed to investigate the link between SARS-CoV-2 infections and myositis. References [1]Witt LJ, et al. The Diagnosis and Treatment of Antisynthetase Syndrome. Clin Pulm Med. 2016 Sep;23(5):218-226. [2]Gracia-Ramos AE, et al. New Onset of Autoimmune Diseases Following COVID-19 Diagnosis. Cells. 2021 Dec 20;10(12):3592. [3]Connors GR, et al. Interstitial lung disease associated with the idiopathic inflammatory myopathies: what progress has been made in the past 35 years? Chest. 2010 Dec;138(6):1464-74. [4]García-Bravo Let al. Association of anti-SARS-COV-2 vaccine with increased incidence of myositis-related anti-RNA-synthetases auto-antibodies. J Transl Autoimmun. 2022 Jun 30;5:100160. ASS patients with positive anti-ARS antibodies per year (from 2015 to 2022). The green line shows the PL7+ patients; and the orange line shows the Jo1+ cases. Acknowledgements I have no acknowledgements to declare. Disclosure of Interests None Declared.

Background Recent data showed that SARS-CoV-2 infection and vaccination could act as a trigger for different autoimmune diseases, including idiopathic inflammatory myopathies (IIM). Objectives The aim of this study was to describe the clinical characteristics of patients diagnosed with IIM following SARS-CoV-2 infection and vaccination in a tertiary rheumatology center. Methods We conducted a retrospective analysis on patients newly diagnosed with IIM, from 1 January 2020 to 31 December 2022, using information from the hospital database. The patients were selected according to the ICD-10 codes indicating IIM (M33.0, M33.1, M33.2, and M33.9). The cases with onset of specific IIM symptoms within 6 months after SARS-CoV-2 infection or vaccination were selected for further analysis. Clinical, biological and immunological parameters were assessed using descriptive statistics. Results A total of 58 patients newly diagnosed with IIM were identified, and in 10 (17.2 %) patients the onset was after SARS-CoV-2 infection (n = 6) or vaccination (n = 4). All patients diagnosed with IIM following vaccination (F:M=1:1, median age 46 years) received a mRNA vaccine and had the clinical onset within several days to a month after vaccination. Among IIM cases following SARS-CoV-2 infection (F:M=1:1, median age 60.5 years), the clinical onset of myopathy was variable, with a minimum of 14 days and a maximum of 6 months after infection. Myalgia, muscle weakness and elevated levels of creatinine kinase were reported in 9 patients. The average CK level was 2534.6 (3760.8) U/L, ranging from 43 to 11827 U/L. Skin lesions were present in all patients with IIM following vaccination and in 4 cases with IIM after SARS-CoV-2 infection. Mechanic’s hands and arthralgia were noted in 5 patients each. Dyspnea and interstitial lung disease (ILD) were reported in 8 cases, with severe pulmonary involvement present in 2 cases. Myocarditis was reported in 2 patients, 1 case from each group. Myositis-specific antibodies (MSAs) and myositis-associated antibodies (MAAs) were reported in 9 patients. Anti-threonyl-tRNA synthetase antibodies (anti-PL7) were present in 5 cases (3 after vaccination and 2 after infection), anti- histidyl-tRNA synthetase antibodies (anti-Jo-1) in 2 patients (in 1 associated with anti-PL7 antibodies), and anti-isoleucyl-tRNA synthetase (anti-OJ antibodies) in 1 patient. ILD was diagnosed in all anti-PL7 antibody positive patients. Conclusion Anti-PL7 antibodies are frequent in newly diagnosed IIM following SARS-CoV-2 infection or vaccination. Further studies are needed to investigate the relationship between SARS-CoV-2 infection and vaccination in the occurrence of IIM. References [1]Galeotti C, Bayry J. Autoimmune and inflammatory diseases following COVID-19. Nat Rev Rheumatol. 2020 Aug;16(8):413–4. [2]Chen Y, Xu Z, Wang P, Li XM, Shuai ZW, Ye DQ, et al. New-onset autoimmune phenomena post-COVID-19 vaccination. Immunology. 2022 Apr;165(4):386–401. Acknowledgements I have no acknowledgements to declare. Disclosure of Interests None Declared.