Periodic fever: From Still's disease to Muckle-Wells syndrome.

Muckle-Wells syndrome is a systemic autoinflammatory disease included in the group of hereditary periodic febrile syndromes. We report the case of a patient with this rare disease to call the attention to the singularity of this condition, its low incidence, its atypical presentation and the subsequent delay in the diagnosis, which is reached when late and devastating consequences have taken place. In this case, the first-line therapy, anti-interleukin 1 (IL-1), failed to control the disease. Nevertheless, the IL-6 inhibitor, tocilizumab, proved effective, achieving the total remission of nephrotic syndrome associated with AA secondary amyloidosis, changing the bleak prognosis of this disease.