Maladie auto-inflammatoire avec hyper-IgD de révélation tardive

Background. The term "auto-inflammatory diseases" encompasses a group of disorders characterised by febrile episodes of sudden onset associated with joint, abdominal, lymph node and cutaneous signs, each presenting a genetic and/or laboratory specificity allowing their identification. Polyclonal elevation of serum IgD is highly suggestive of hyper-IgD syndrome, a disease with autosomal recessive transmission that usually begins before the age of one year. Case report. We report the case of a 46-year-old woman presenting a disease since the age Of 30 years clinically very similar to hyper-IgD syndrome except for ocular and pulmonary involvement. However, tests revealed neither mevalonate kinase gene mutation nor elevation of urinary mevalonic acid. The near-monthly attacks were controlled with mycophenolate mofetil. Discussion. Three cases with identical clinical and laboratory profiles have been reported in the literature and diagnosed as late-onset hyper-IgD syndrome. Our case is the only one involving indirect screening for mutation of the mevalonate kinase gene, which proved negative. This finding rules out the diagnosis of classic hyper-IgD syndrome in our case and raises the possibility of auto-inflammatory disease with reactional hyper-IgD of a different cause, either acquired or secondary to an as yet unidentified mutation.