RESUMEN
Idiopathic multicentric Castlemans disease is a rare lymphoproliferative disorder that has many similar laboratory, radiological, clinical and pathological manifestations with various conditions, including IgG4-related disease. Increased activity of cytokines, especially interleukin-6, leads to systemic inflammatory symptoms with the development of lymphadenopathy and rarely extranodal lesions. Histological changes in the lymph nodesin hyaline vascular and plasma cell variants of Castlemans disease are hardly distinguishable from the pattern of reactive, tumor and IgG4-related lymphadenopathy. Idiopathic multicentric Castlemans disease can be diagnosed only when infection with human herpesvirus-8 type and human immunodeficiency virus is excluded. In the article, the authors describe two cases of idiopathic multicentric Castlemans disease, including the first world literature description of extranodal damage of the hip muscle in this disorder. In addition, the authors gave a review of the literature on the main clinical, laboratory and morphological manifestations, which allow confirming the diagnosis of Castlemans disease.