Beyond Resnick and Niwayama: a structured narrative literature review on the clinical and imaging phenotypes of diffuse idiopathic skeletal hyperostosis (DISH).

Since 1975, the Resnick and Niwayama classification criteria have served as the standard framework for defining diffuse idiopathic skeletal hyperostosis (DISH) in research. These criteria predominantly identify advanced disease. Accumulating evidence towards an updated definition of DISH is warranted. In this review we aimed to re-evaluate the definition of DISH in light of contemporary evidence and identify elements that may inform future classification criteria.A literature review was conducted of studies published between 1975 and 2025. Data extraction targeted imaging features, including site-specific bone formation and pre-DISH characteristics, as well as clinical features, functional outcomes and available markers. Findings were qualitatively synthesised.119 studies were included. Imaging data indicated that degenerative spinal disease alone is insufficient to exclude DISH. Bony bridges most commonly affect the thoracic spine, though involvement of the cervical and lumbar regions is well documented. Disease progression is typically slow, and frequent entheseal involvement of pelvic, chest wall and peripheral sites. Epidemiological data demonstrate a rising prevalence with age and a male predominance. DISH shows strong association with metabolic syndrome, type 2 diabetes, elevated body mass index, raised systolic blood pressure, dyslipidaemia, hyperuricaemia and cardiovascular disease. Inflammatory markers are generally within normal ranges. Evidence regarding physical impairment remains mixed, with some studies reporting reduction in spinal mobility and chest expansion alongside broader functional limitations.This review moves beyond the Resnick and Niwayama criteria to offer an updated framework to support the development of future DISH classification criteria, particularly to earlier disease stages.