Rheumatologic Perspectives on Sarcoidosis: Predicting Sarcoidosis-Associated Arthritis Through Comprehensive Clinical and Laboratory Assessment

<b>Background/Objectives:</b> The primary aim of our study was to evaluate the demographic, clinical, and laboratory characteristics of sarcoidosis patients with musculoskeletal symptoms; investigate the relationship between arthritis development and various laboratory parameters (such as vitamin D, liver enzymes, and ACE levels); and compare the sarcoidosis-associated arthritis cases with those without. We also explored the factors influencing arthritis development and the role of biopsy in diagnosing sarcoidosis within rheumatology practice. <b>Methods:</b> This retrospective study analyzed 147 sarcoidosis patients from 2000 to 2024, categorized by the presence (<i>n</i> = 45) or absence (<i>n</i> = 102) of arthritis. Demographic, clinical, and laboratory data, including biopsy results, were collected and compared. <b>Results:</b> The mean age was 56.02 ± 11.21 years, with a mean disease duration of 134.33 ± 56.98 months. Females constituted 86.4% of the cohort. All of the patients presented musculoskeletal involvement. Pulmonary involvement was present in 93.7% of cases, and extrapulmonary involvement included the skin (21.20%), the eyes (14.30%), and peripheral lymphadenopathy (10.6%). Methotrexate was the most common treatment after corticosteroids. In the arthritis group, diabetes mellitus was more frequent (<i>p</i> = 0.024), the GGT levels were higher (<i>p</i> = 0.044), and the 25-hydroxyvitamin D levels (<i>p</i> = 0.002) and the DLCO Adj (<i>p</i> = 0.039) were lower. Multivariable regression showed diabetes mellitus (<i>p</i> = 0.028, OR: 4.805, 95% CI: 1.025-22.518) and low 25-hydroxyvitamin D levels (<i>p</i> = 0.034, OR: 0.914, 95% CI: 0.841-0.993) as factors influencing arthritis development. The other parameters showed no significant differences. <b>Conclusions:</b> This study identified significant clinical, demographic, and laboratory differences between sarcoidosis patients with and without arthritis. The patients with sarcoidosis-associated arthritis exhibited a higher frequency of diabetes mellitus, lower levels of 25-hydroxyvitamin D, and elevated GGT levels. Additionally, the lower DLCO values in the patients with arthritis indicate a more severe impact on pulmonary function, underscoring the importance of comprehensive pulmonary evaluation in this subgroup.