Biopsy-proven granulomatous neuromyopathy in a case of Blau syndrome

A 37-year-old woman with Blau syndrome was extensively investigated for a rapidly progressive ascending sensorimotor polyneuropathy initially thought to be Guillain-Barré syndrome. The patient's symptoms progressed despite intravenous immunoglobulin therapy, with increasingly asymmetric involvement suggestive of mononeuritis multiplex, a pattern confirmed on nerve conduction studies. As her symptoms failed to respond to treatment, the question arose whether or not granulomatous inflammation in Blau syndrome (congenital autoinflammatory granulomatous polyarthritis, dermatitis, and uveitis) might be responsible for this presentation. A review of the published literature on Blau syndrome suggested this to be highly unlikely, but sural nerve and quadriceps muscle biopsies revealed active granulomatous inflammation of affected axons and muscles. To our knowledge, histopathological involvement of these tissues has not been reported previously in Blau syndrome.