Diffuse idiopathic skeletal hyperostosis (DISH): is it of vascular aetiology?

OBJECTIVE Reassessment of the pathological features of spinal involvement in DISH and studying the possible aetiopathogenetic mechanism/s of DISH in view of clinical, radiological and pathological findings. METHODS Forty Egyptian patients with DISH were included in this study. They underwent clinical and radiological assessment. Routine lab tests were done in addition to measuring blood sugar, serum lipids and uric acid. Pathologic study of 50 macerated specimens of fused spines fulfilling the criteria of DISH was also performed. A pathologic study of another 50 macerated specimens from normal spines were examined as a control. RESULTS Radiological assessment showed spinal involvement in 100% of the patients in the lower thoracic region, while it was present in 75%, 70% and 55% in the upper thoracic, lumbar and cervical regions respectively. Pathological study revealed a significant increase in the number and width of nutrient foramina, denoting hypervascularity of the ossified ligaments and vertebrae involved (P < 0.001), in addition to a significant (P < 0.001) increase in the size of the affected vertebrae, pointing to the possible role of a vascular disorder in the disease pathogenesis. Metabolic disorders were evident among our group of patients in the form of obesity (50%), hyperlipidemia (80%), diabetes mellitus (60%), and hypertension (45%). CONCLUSION DISH is a diffuse systemic condition which is most probably related to abnormal bone cell growth/activity reflecting the influence of metabolic factors that lead to new bone deposition. The vertebral blood supply is a predisposing factor that contributes to the onset/progression and/or localization of DISH.