Predictive value of bone scintigraphy for the detection of joint involvement in Behcet's disease: Dermatologists' perspectives

Background: Behget's disease (BD) is a multisystemic inflammatory disease with articular involvement. Non-specific arthralgia without objective signs of arthritis, such as swelling or effusion, is common in such patients. Thus, an accurate diagnosis of joint involvement may be challenging for dermatologists. Objectives: To evaluate the validity of Tc-99m-methylene diphosphonate (Tc-99m-MDP) bone scintigraphy for joint involvement assessment in patients with BD. Materials and methods: In 211 patients with BD who had scintigraphic evaluations due to joint symptoms, agreement between bone scintigraphy findings and clinically evaluated joint complaints was retrospectively assessed using Cohen's kappa (kappa) statistic. A patient subset (n = 104) showing agreement between joint complaints and scintigraphy results was re-evaluated by a rheumatologist to determine the level of diagnostic specificity attained by combining bone scintigraphy with clinical examinations of dermatologists. Results: The total kappa value (211 patients) was 0.604, indicating fair agreement between joint complaints and scintigraphy results. Individual analysis of eleven joint categories revealed statistically significant correlations for wrist (kappa = 0.677), shoulder (kappa = 0.661), and foot joints (kappa = 0.618). Of the 104 referrals to a rheumatologist, 95 (91.34%) were confirmed as having BD-associated articular involvement. Joint acral areas (e.g., foot, hand, wrist and shoulder) that had the highest kappa value correlations also ranked highest in diagnostic specificity. Conclusion: Bone scintigraphy presents a simple and useful option for dermatologists to assess joint involvement in BD patients, especially for specific anatomic sites.