We report a 73-year-old female patient with Castleman's disease coexistent with large B cell type non-Hodgkin's lymphoma in a right axillary lymphadenopathy. An excisional biopsy was performed: microscopically, the lymph node revealed the presence of numerous plasma cells and small lymphoid cells characteristic of Castleman's disease. An analysis of another portion of the specimen revealed lymphoid cells with large abnormal nuclei gathered locally that were CDD 79+, CD 38+ and MUM-1+ as well as positive for Kaposi sarcoma-associated herpesvirus and negative for Epstein Barr virus encoded RNA-1 (EBER).