We report five cases that presented with high fever, anasarca, hepatosplenomegaly and severe thrombocytopenia with reticulin fibrosis of the bone marrow. The constellation of symptoms is not compatible with any known disease, and we had difficulty in diagnosis and treatment. The age distribution was from 47 to 56 years, and two men and three women were affected. Two patients needed hemodialysis because of renal dysfunction and oliguria with massive pleural effusion. Laboratory examinations showed normal immunoglobulin levels and no monoclonal protein. None of them showed diagnostic autoantibodies for any autoimmune diseases. Histological examination of the liver in three patients and spleen in two showed non-specific findings. Lymphadenopathy was tiny and lymph node biopsy was carried out in only one case. Histologically, paracortical hyperplasia with vascular proliferation and atrophic germinal centers resembling hyaline-vascular-type Castleman's disease or POEMS syndrome were detected. Without a definitive diagnosis, treatment was started with cyclophosphamide, hydroxydaunorubicin, vincristine and prednisolone (CHOP) regimen in one patient, semi-pulse therapy with methyl-predonisolone in three and cyclosporin A in three. Two patients achieved complete remission, two were steroid-dependent and the remaining one died of multiple organ failure. These findings suggest that this disease may be a novel clinical entity belonging to systemic inflammatory disorder with a background of immunological abnormality or a unique variant of multicentric Castleman's disease. [J Clin Exp Hematop 53(1): 63-68, 2013]