Occipital Enthesophyte in Axial Spondyloarthritis: Report of two cases

Axial spondyloarthritis (axSpA) is a chronic inflammatory condition primarily affecting the sacroiliac joints and spine, with enthesitis as its hallmark feature. While enthesitis commonly involves lower limb sites, cranial localizations, such as the external occipital protuberance, are exceptionally rare. We report two cases of young male patients with long-standing axSpA presenting with occipital enthesophytes. A 34-year-old male with juvenile-onset axSpA exhibited bilateral sacroiliitis, coxitis, and cervical stiffness. A 33-year-old male with chronic polyarthritis since adolescence showed advanced axial and peripheral structural damage. Cervical radiographs in both revealed an enthesophyte at the external occipital protuberance. Laboratory findings indicated elevated inflammatory markers, with HLA-B27 positivity in one patient. Treatment with TNF inhibitors (etanercept and golimumab) resulted in clinical improvement. These cases highlight the importance of comprehensive imaging to identify rare entheseal sites in axSpA, enabling tailored therapeutic strategies.