Reactive arthritis is a sterile inflammatory arthritis that arises following a gastrointestinal or genitourinary tract infection, most frequently triggered by organisms such as Chlamydia trachomatis, Salmonella spp, Shigella spp, Yersinia spp, and Campylobacter spp. Reactive arthritis is classified as a seronegative spondyloarthropathy and shares characteristics with related conditions such as psoriatic arthritis and ankylosing spondylitis, but reactive arthritis is uniquely defined by its temporal association with a preceding infection. Initial symptoms typically present as acute, asymmetric oligoarthritis or monoarthritis within 1 to 6 weeks of infection, and persistent inflammation may lead to prolonged discomfort or disability in some individuals. The condition primarily affects the large joints of the lower extremities, though axial involvement may also occur. Enthesitis is a hallmark feature. Extra-articular findings are frequent and may precede, coincide with, or follow joint involvement. These findings may involve the eyes (conjunctivitis or uveitis), genitourinary tract (urethritis or cervicitis), or skin, including lesions such as keratoderma blenorrhagicum and circinate balanitis. The clinical course varies widely; while many cases resolve within several months, up to 30% of patients develop chronic or recurrent symptoms, and some progress to chronic spondyloarthritis. Reiter syndrome, historically used to describe the triad of arthritis, urethritis, and conjunctivitis after an inciting infection, represents only a subset of reactive arthritis. The term has fallen out of favor, both because it fails to capture the full clinical spectrum and due to ethical concerns regarding Hans Reiter’s role in human rights abuses. Reactive arthritis is now the preferred, more accurate term for this postinfectious inflammatory condition.

Psoriatic arthritis is a chronic inflammatory disease associated with psoriasis, and its diagnosis can be challenging owing to nonspecific symptoms, absence of reliable biomarkers, and occasional delay in skin manifestations. Herein, we report a case of psoriatic arthritis that initially presented as an acute finger inflammation mimicking infection. A 46-year-old woman developed sudden swelling and pain in the left ring finger during chemotherapy for cervical cancer. Based on the results of the physical examination, laboratory tests, and magnetic resonance imaging, pyogenic flexor tenosynovitis was suspected, and synovectomy was performed; however, bacterial and mycobacterial cultures yielded negative results. Despite the administration of antibiotics, the inflammation persisted, and she was referred to the Rheumatology Department, where she was diagnosed with reactive arthritis secondary to Chlamydia infection. Although the inflammation improved after antimicrobial therapy, the finger swelling persisted. Follow-up magnetic resonance imaging and serological testing were performed, and the patient was diagnosed with seronegative rheumatoid arthritis. Four years after onset, erythematous skin lesions appeared, and dermatological evaluation confirmed plaque psoriasis; thus, a definitive diagnosis of psoriatic arthritis was established. Disease-modifying antirheumatic drug adjustments improved symptoms, but residual 'pencil-in-cup' deformity and limited finger motion remained. This case highlights the difficulty in diagnosing psoriatic arthritis when arthritis precedes skin lesions. Clinicians should consider psoriatic arthritis in persistent or refractory arthritis and carefully monitor skin and nail changes to achieve an earlier diagnosis and prevent irreversible joint damage.

Seronegative spondyloarthropathy (SpA) and Takayasu's arteritis (TA) are distinct chronic inflammatory conditions with autoimmune characteristics. While both conditions are relatively common, their concurrent occurrence is rare. This case report presents an individual diagnosed with both SpA and TA, detailing the clinical presentation, disease course, and therapeutic interventions. A review of relevant literature is also included to enhance clinical awareness of this uncommon combination. For that patients with SpA who exhibit elevated inflammatory markers, intermittent low-grade fever, fatigue, or inadequate response to standard therapies, it's better to undergo evaluation for the potential presence of TA. Early identification of TA in such cases may help mitigate the risks of misdiagnosis or delayed diagnosis.

Whole-body MRI (wbMRI) is an advanced scan modality which provides high-contrast resolution images of the entire body for screening, diagnosis, staging, and surveillance purposes. Thanks to recent technological advancements, wbMRI has gained increasing attention as a valuable tool for diagnosing and monitoring systemic arthritides by virtue of its comprehensive coverage. This technology is particularly beneficial for inflammatory conditions like rheumatoid arthritis, seronegative spondyloarthropathy, juvenile idiopathic arthritis, and chronic aseptic osteitis, all characterized by multifocal involvement of both skeletal and extra-skeletal sites. Unlike conventional MRI targeting symptomatic areas, wbMRI enables concurrent early detection also of subclinical disease foci, providing a more accurate assessment of the total disease burden. Compared to plain radiography, conventional ultrasound, and targeted MRI, wbMRI offers better sensitivity and reproducibility, particularly for intraosseous findings and axial involvement. In addition, wbMRI can be tailored to specific clinical needs through customizable scan protocols, and the lack of ionizing radiation makes it ideal for monitoring autoimmune diseases also in sensitive cohorts. Although wbMRI holds great potential for improving diagnostic accuracy and patient outcomes in inflammatory arthritis, further research is needed to validate standard scan protocols, to confirm their cost-effectiveness, and to integrate them into routine clinical practice. The present article aims to overview the current wbMRI technology and discuss it in the context of inflammatory arthritis. A general wbMRI protocol for non-oncologic musculoskeletal application is also provided.

Reactive arthritis is included in the spectrum of seronegative spondyloarthritides, occurring secondary to triggers of genitourinary and gastrointestinal tract infections. We describe a case of sexually acquired reactive arthritis in an MSM, associated with extragenital Mycoplasma genitalium infection. Mycoplasma genitalium was detected from rectal swab by Real-Time PCR assays.

A 79-year-old male patient on hemodialysis for 29 years was admitted to the hospital with unexplained fever (C-reactive protein, 16.1 mg/dL), anemia (hemoglobin 7.6 g/dL), and multiple joint swelling that began 7 months earlier. Infection was ruled out, both rheumatoid factor and anti-cyclic citrullinated peptide antibodies were negative. Positron emission tomography-computed tomography showed positive findings in bilateral shoulder joints, palmar region, femoral head area, and cervical spine. Magnetic resonance imaging showed low intensity on T1 and low-normal intensity on T2, especially in the shoulder joint. Musculoskeletal ultrasound revealed hypoechoic material with surrounding fluid collection and Doppler signals indicating blood flow in the shoulder joint, resembling synovitis associated with rheumatoid arthritis. Biopsy of the shoulder joint mass showed positive Congo-red and direct fast scarlet staining, positive β2-microglobulin, and infiltration of CD68-positive macrophages. Given the history of previous carpal tunnel release and cervical destructive spondyloarthropathy, dialysis-related amyloidosis, and amyloid-related arthritis were diagnosed. However, as the case had the feature of rheumatoid arthritis-like synovitis, tocilizumab was initiated, resulting in improved anemia and Clinical Disease Activity Index. We speculate that dialysis-related amyloidosis can present with arthritis involving cytokines, similar to rheumatoid arthritis, and tocilizumab may be effective for the resulting synovitis.

Seronegative spondyloarthritis (SpA) comprises a heterogeneous group of rheumatic diseases characterized by axial and peripheral joint involvement, as well as extra-articular manifestations, including uveitis, psoriasis, and inflammatory bowel disease. Although renal involvement in SpA is less understood, evidence suggests it may result from disease activity, chronic inflammation, or therapeutic agents. The underlying pathophysiology remains unclear. This systematic review evaluates the prevalence and risk factors associated with renal abnormalities in SpA. A systematic literature search was conducted following the latest Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data from 26 studies published between 1980 and 2025 were synthesized. Extracted variables included study author, year and location of publication, sample size, renal assessment parameters, prevalence of renal involvement, presence of control groups, and statistical significance of findings. Renal involvement in SpA, assessed through hematuria, proteinuria, estimated glomerular filtration rate, and International Classification of Diseases codes, showed considerable variability, with prevalence ranging from 0.2 to 77.5%. Nephrolithiasis was also more common among SpA patients, with reported rates between 1.6% and 29.1%. Potential risk factors, including age, disease activity, comorbidities, and HLA-B27 status, were explored, though findings remained inconsistent. This review highlights significant methodological discrepancies among studies assessing renal involvement in SpA. Further research is needed to clarify the renal complications associated with SpA and establish reliable risk factors. PROSPERO Registration: CRD42024579791.

Spondyloarthropathies (SpAs) represent a diverse group of seronegative immune-mediated inflammatory diseases characterized by a genetic predisposition and an association with human leukocyte antigen-B27. This narrative review aims to explore juvenile spondyloarthropathies (JSpAs), their classification, clinical manifestations, diagnostic challenges, and contemporary treatment strategies. According to the International League of Associations for Rheumatology criteria, JSpAs include several specific forms: enthesitis-related arthritis, psoriatic arthritis, and undifferentiated arthritis. Despite established classifications, the terms and definitions surrounding these conditions can often lead to confusion among healthcare professionals. This ambiguity underscores the need for a standardized approach to nosological classification. The clinical presentation of JSpAs can be multifaceted, encompassing both articular and extra-articular manifestations. Articular symptoms may include enthesitis and varying forms of arthritis, while extra-articular involvement can range from uveitis to gastrointestinal, cardiovascular, pulmonary, neurological, and renal complications. These diverse manifestations highlight the systemic nature of the disease and the importance of a holistic approach to diagnosis and treatment. While laboratory tests for SpAs are often non-specific, imaging modalities such as musculoskeletal ultrasound and magnetic resonance imaging play a crucial role in the early detection of inflammatory lesions. These imaging techniques can provide valuable insights into disease progression and aid in the formulation of appropriate treatment plans. Current treatment guidelines advocate for a "stepwise" approach to therapy, beginning with nonsteroidal anti-inflammatory drugs and progressing to glucocorticoids, disease-modifying antirheumatic drugs, and biological agents, particularly anti-tumor necrosis factor alpha agents. The primary objective of treatment is to achieve clinical remission or, at a minimum, to attain low disease activity. Regular monitoring of disease activity is imperative; however, the lack of validated assessment tools for the pediatric population remains a significant challenge. JSpAs pose unique challenges in terms of diagnosis and management due to their diverse manifestations and the complexities of their classification. Ongoing research and clinical efforts are essential to refine our understanding of these conditions, improve treatment outcomes, and enhance quality of life for affected children and their families. Effective management hinges on early detection, individualized treatment plans, and continuous monitoring, ensuring that patients receive the most appropriate care tailored to their specific needs.