Nuclear medicine has become an indispensable discipline in the diagnosis and management of musculoskeletal infections. Radionuclide tests serve as a valuable diagnostic tool for patients suspected of having osteomyelitis, spondylodiscitis, or prosthetic joint infections. The choice of the most suitable imaging modality depends on various factors, including the affected area, potential extra osseous involvement, or the impact of previous bone/joint conditions. This review provides an update on the use of conventional radionuclide imaging tests and recent advancements in fusion imaging scans for the differential diagnosis of musculoskeletal infections. Furthermore, it examines the role of radionuclide scans in monitoring treatment responses and explores current trends in their application. We anticipate that this update will be of significant interest to internists, rheumatologists, radiologists, orthopedic surgeons, rehabilitation physicians, and other specialists involved in musculoskeletal pathology.

Background/Objectives: Anti-neutrophil cytoplasmic antibodies (ANCAs) have been found in interstitial lung disease (ILD) in recent years, although its impact on ILD prognosis is less known. To date, ANCAs are not included in the interstitial pneumonia with autoimmune features (IPAF) definition criteria. Therefore, ANCA-ILD, in the absence of known ANCA-associated vasculitis (AAV), could be underdiagnosed. Our aim was to analyze the clinical profile and prognosis of ANCA-ILD patients. Methods: Patients diagnosed with ILD and positive ANCA were enrolled in a retrospective, monocentric cohort study. Lung function outcomes and mortality were assessed according to clinical, serological, radiological, and treatment characteristics. Survival was analyzed using Kaplan–Meier curves and Cox regression models. Results: A total of 23 patients were included, mostly women, with a median time from ILD diagnosis of 36 (24–68) months and a predominant anti-MPO pattern (56.5%). Nearly half of the patients had AAV, mostly microscopic polyangiitis (MPA). The presence of AAV was significantly associated with anti-MPO antibodies and an NSIP radiographic pattern. Overall, the fibrotic pattern (either UIP or fibrotic NSIP) was the most common (73.9%), mainly UIP (51.2%). However, it appeared less frequently in the AAV-ILD group. During follow-up, lung function impairment or radiological progression was observed in 65.2% of patients. Cumulative mortality incidence was high (43.4%), largely due to ILD itself (80%). A UIP pattern was associated with a higher and earlier mortality (HR 34.4 [1.36–132]), while the use of immunosuppressants showed a trend towards lower ILD-related death. Conclusions: In our cohort, ANCA-ILD patients mostly presented with fibrotic patterns, with AAV in almost half of the cases and a high and early mortality rate, which suggests the need to assess ANCA in all ILD patients.

The aim of this study was to identify single-nucleotide polymorphisms (SNPs) in bone remodeling-related genes associated with disease severity and bone mineral density (BMD) in early arthritis (EA) patients. For this purpose, the genotyping of 552 SNPs located in gene regions of semaphorins 4b, 4d, 4f, DKK1, 2 and 3, sclerostin, OPG, RANK and RANKL was performed using Immunochip from Illumina Inc. in 268 patients from the Princesa Early Arthritis Register Longitudinal (PEARL) study. Measurements of BMD and disease activity were chosen as outcome variables to select SNPs of interest. The relationships of SNPs with the BMD of the forearm, lumbar spine and hip (Hologic-4500 QDR) were analyzed by linear regression adjusted for age, sex, body mass index and presence of anti-citrullinated peptide antibodies (ACPAs). The association of each SNP with activity variables was analyzed by linear regression, logistic regression or ordered logistic regression according to the variable, and multivariate models were adjusted for potentially confounding variables, such as age, sex and presence of ACPAs. These analyses showed that four SNPs located in the genes coding for RANK (TNFRSF11A) and OPG (TNFRSF11B) were significantly associated with clinical variables of severity. SNP rs1805034 located in exon 6 of TNFRSF11A, which causes a non-synonymous (A/V) mutation, showed significant association with BMD and therefore may be considered as a possible biomarker of severity in RA patients. SNPs in the OPG gene showed an association with serum OPG levels and predicted disease activity after two years of follow-up.

Objective: To investigate the prevalence and clinical spectrum of atypical or non-classical complications in adult-onset Still’s disease (AOSD) beyond macrophage activation syndrome (MAS) and to identify factors linked to their occurrence. Methods: Multicenter cross-sectional study of AODS cases included in the Spanish registry on Still’s disease. Results: This study included 107 patients (67% women), of whom 64 (59.8%) developed non-classical complications. These include macrophage activation syndrome in 9.5%, atypical skin manifestations in 38.8%, cardiac involvement in 22.7% (comprising pericarditis, myocarditis, pulmonary arterial hypertension, and noninfectious endocarditis), pleuritis in 28.9%, transient pulmonary infiltrates in 4%, significant headache in 14.1%, lower abdominal pain with evidence of peritonitis in 8.4%, and secondary amyloidosis in 0.9%. In the multivariate logistic regression analysis, lymphadenopathy (OR 2.85, 95% CI 1.03–7.91, p = 0.044) and the systemic score system (SSC) index (OR 1.86, 95% CI 1.29–2.69, p = 0.001) were independently associated with the development of non-classical clinical manifestations. In contrast, typical exanthema was associated with a reduced risk of these complications (OR 0.32, 95% CI 0.11–0.95, p = 0.041). Conclusions: In addition to the typical clinical manifestations and MAS, a significant proportion of patients with AOSD develop uncommon complications, some of which can be potentially life-threatening. These should be considered in the evaluation and follow-up of patients. Early recognition and prompt management are crucial to significantly reduce morbidity and mortality.