RESUMEN
Background: Diffuse idiopathic skeletal hyperostosis and spondyloarthritis share similarities in clinical and radiological findings. In this article, we report a case of overlapping of these two hyperostotic diseases followed by an extensive narrative review of the literature focusing on the gray areas in the diagnosis of diffuse idiopathic skeletal hyperostosis. Case description: We report the case of simultaneous diffuse idiopathic skeletal hyperostosis and ankylosing spondylitis in a 57-year-old man. The diagnosis was made after many collegial meetings based on solid radiological arguments. Conclusion: Review of the literature reveals many uncertainties in the diagnosis of diffuse idiopathic skeletal hyperostosis, especially in the radiological evaluation of sacroiliac joints. Diffuse idiopathic skeletal hyperostosis and ankylosing spondylitis frequently overlap in important radiological features leading to diagnostic ambiguity and they can also co-exist in the same patient.