Dercum's disease, or adiposis dolorosa, is a rare condition of unknown aetiology characterized by overweight or obesity in combination with painful adipose tissue. We report the case of a 67-year-old woman in whom a form of Dercum’s disease appeared after the intake of Tocilizumab, an anti-interleukin-6 receptor monoclonal antibody to treat her rheumatoid arthritis. The temporal relationship that undoubtedly exists between the drug intake and the outset of the adiposis might help in a better knowledge of the pathogenesis of this disease. We reviewed the relevant Literature focusing on different strands of evidence which point to the pathological mechanism of this disorder.