(1) Background: A tophus is a clinical manifestation of advanced gout, and in some patients could lead to joint deformities, fractures, and even serious complications in unusual sites. Therefore, to explore the factors related to the occurrence of tophi and establish a prediction model is clinically significant. (2) Objective: to study the occurrence of tophi in patients with gout and to construct a predictive model to evaluate its predictive efficacy. (3) Methods: The clinical data of 702 gout patients were analyzed by using cross-sectional data of North Sichuan Medical College. The least absolute shrinkage and selection operator (LASSO) and multivariate logistic regression were used to analyze predictors. Multiple machine learning (ML) classification models are integrated to analyze and identify the optimal model, and Shapley Additive exPlanations (SHAP) interpretation was developed for personalized risk assessment. (4) Results: Compliance of urate-lowering therapy (ULT), Body Mass Index (BMI), course of disease, annual attack frequency, polyjoint involvement, history of drinking, family history of gout, estimated glomerular filtration rate (eGFR), and erythrocyte sedimentation rate (ESR) were the predictors of the occurrence of tophi. Logistic classification model was the optimal model, test set area under curve (AUC) (95% confidence interval, CI): 0.888 (0.839–0.937), accuracy: 0.763, sensitivity: 0.852, and specificity: 0.803. (5) Conclusions: We constructed a logistic regression model and explained it with the SHAP method, providing evidence for preventing tophus and guidance for individual treatment of different patients.

Restless Legs Syndrome (RLS) is a common neurological disorder characterized by an irresistible urge to move the legs, often accompanied by uncomfortable sensations. These symptoms typically worsen during periods of rest or in the evening and are partially or temporarily relieved by movement. Variant RLS is diagnosed when these core symptoms extend to extra-leg regions—such as the arms, abdomen, or bladder—while still fulfilling the diagnostic criteria established by the International Restless Legs Syndrome Study Group. We report a case of an adult female patient with refractory right shoulder pain, ultimately diagnosed as variant RLS. Initially misdiagnosed as frozen shoulder, the correct diagnosis was confirmed through polysomnography, which revealed an elevated Periodic Limb Movement during Sleep index, and a supportive International RLS Rating Scale score. Following targeted treatment involving iron supplements for iron deficiency anemia and pramipexole for symptomatic relief, the patient’s shoulder pain and other associated symptoms improved markedly. This case expands the known clinical spectrum of variant RLS by illustrating a pain-dominant upper limb phenotype. Furthermore, we provide a summary analysis of previously reported cases of restless arms syndrome, highlighting the importance of including variant RLS in the differential diagnosis for patients presenting with unexplained shoulder or arm discomfort.