Idiopathic multicentric Castleman disease preceded by cutaneous plasmacytosis successfully treated by tocilizumab

A woman aged 45 years with a 1.5-year history of violaceous plaques on the forehead and chest presented with fever, weight loss and aggravation of the plaques. Inflammatory markers and interleukin-6 level were elevated, and superficial lymphadenopathies and splenomegaly were identified by CT scan. Immunohistochemical findings of the lymph node and the skin showed polyclonal plasmacytosis and follicular hyperplasia, leading to the diagnosis of idiopathic multicentric Castleman disease (iMCD) after human herpesvirus-8 infection was excluded. The patient was successfully treated with anti-interleukin-6 receptor antibody, tocilizumab, following relapse after prednisolone therapy. Our literature review found 11 case reports of pathologically confirmed iMCD preceded by cutaneous plasmacytosis. The median duration of asymptomatic phase with only skin lesions was 7.5 years, whereas the phase lasted only for 1.5 years in our case. iMCD can develop shortly after asymptomatic cutaneous plasmacytosis. Tocilizumab can be a treatment of choice for this type of iMCD.