Bullhead Sign in SAPHO Syndrome
A local male in his mid-40s had a 10-year history of pain over both clavicles and sternoclavicular joints. In May 2023, he visited the outpatient rheumatology clinic where physical examination demonstrated enlarged clavicles (Figure 1A) (arrows) but no cutaneous manifestations. Laboratory tests disclosed elevated erythrocyte sedimentation rate (84 mm/h; reference, <16 mm/h), increased C-reactive protein levels (113 mg/L; reference, <8 mg/L), absent human leucocyte antigen-B27, and negative culture results.
