A 48-year-old woman was hospitalized because of severe thrombocytopenia, leg edema, and fever. Intravenous immunoglobulin therapy was administered, but no efficacy was obtained. Her bone marrow was dry-tap, and fibrosis was found in the biopsy specimens. A positron emission tomographic study showed FDG-avid lymphadenopathy and hepatomegaly. Biopsy specimens of axillary lymph nodes showed Castleman's disease-like findings. Since she then developed severe proteinuria and massive pleural effusion, steroid therapy was started, providing temporary relief of symptoms other than the thrombocytopenia. However, rapid worsening of her general condition prompted us to attempt rituximab as salvage therapy. The pleural effusion, edema, and proteinuria disappeared soon after starting rituximab administration. Platelet counts also normalized and fibrosis of the bone marrow showed amelioration. Recently, a variant of multicentric Castleman's disease, termed the TAFRO syndrome, has been proposed, and our patient's features fit the diagnosis of this syndrome. Rituximab might be considered as a therapeutic option in such cases.