102. When Multiple Sclerosis and Neuro Behcet Disease Meet: What Management to Adopt?

The association between two autoimmune diseases is frequently observed in the context of an overlap syndrome, but the association between MS and neuro-Behcet's disease is rarely observed. The differential diagnosis between the two is often difficult in routine practice. We report 6 patients (1 man and 5 women), diagnosed as MS or Behcet's disease, but who subsequently presented clinical and radiological criteria of the other condition, and who met the international criteria of the 2 conditions. 4 patients met the 2017 McDonald criteria of MS and had been initially treated with interferons. Subsequently, signs of Neuro Behcet appeared and treatment straddling both conditions was proposed. 2 patients were previously followed for Behcet's disease but their imaging met Barkhoff's radiological criteria and the lumbar puncture had found a persistent oligoclonal peak. The distinction between MS and neuro-Behcet's disease can be difficult when neurological disorders are isolated or inaugurate the disease in Behcet's disease. This causes diagnostic and therapeutic delay. The frequency of both conditions in the Mediterranean basin makes neuro-Behcet's disease the main differential diagnosis to be considered in the presence of MS.