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A 47-year-old man presented at a local ophthalmological hospital with blurred vision. He had been diagnosed with hypertensive retinopathy and renal failure and was referred to our hospital for treatment. A renal biopsy was done to evaluate pathology of high proteinuria, hematuria, and rapidly progressive glomerulonephritis. Blood pressure remained high despite antihypertensive therapy; anemia and thrombocytopenia gradually progressed. Thrombotic microangiopathy (TMA) was suspected based on red blood cell fragmentation due to hemolytic anemia, thrombocytopenia, and renal failure. However, plasma exchange resolved neither thrombocytopenia nor renal failure, and anemia gradually progressed. Backache suddenly developed 13 days later, and CT findings indicated a retroperitoneal hematoma secondary to bleeding from the kidney. Selective renal artery embolization via angiography stopped the bleeding, but the patient went into hemorrhagic shock. Pathological findings on renal biopsy were identical to those in malignant hypertension, namely an edematous membrane lining, thickened arterioles, and stenosis. We diagnosed thrombotic microangiopathy due to malignant hypertension, without decrease in activities of ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 motif) or its antibodies. Renal failure did not improve, and continuous hemodiafiltration was needed. This procedure stabilized blood pressure and improved the TMA.

A 71-year-old woman who had been treated with methotrexate (MTX) and prednisolone for rheumatoid arthritis since 2010 presented with hematuria. Cystitis was diagnosed. Chest and abdominal CT images revealed a bladder tumor, with lung and bilateral adrenal metastases. Transurethral resection of the bladder tumor (TUR-BT) confirmed these findings in September 2014. Histological findings of the bladder included large atypical lymphoid cells indicating diffuse large B-cell lymphoma. After TUR-BT, CT imaging showed that the tumor had shrunk. Still, MTX was continued. She was diagnosed with MTX-related lymphoproliferative disorders in November 2014 and MTX was discontinued. Fluorodeoxyglucose-positron emission tomography on March 2015 showed a complete response.

Acquired amegakaryocytic thrombocytopenic purpura (AATP) is a rare disorder characterized by severe thrombocytopenia associated with total absence or a selective decrease in bone marrow megakaryocytes. A 67-year-old male presented with a 2-month bleeding tendency. He was referred to our hospital because of severe thrombocytopenia. Bone marrow biopsy showed complete absence of megakaryocytes without dysplasia in cells of the myeloid and erythroid lineages. AATP was diagnosed. In addition, mild normocytic normochromic anemia and reticulocytosis were also observed and haptoglobin was below the detectable level. Coombs-negative autoimmune hemolytic anemia (AIHA) was diagnosed based on the high titer of RBC-bound IgG and negative direct and indirect coombs test results. He was first treated with cyclosporine 200 mg per day and subsequently with prednisolone but only slight temporary improvement was achieved. Administration of eight doses of rituximab 375 mg/m(2) per week ameliorated both thrombocytopenia and anemia. AATP should be considered in the differential diagnosis of thrombocytopenia, and immunosuppressive therapy is a potential first-line treatment. This is the first case report of AATP accompanied by AIHA successfully treated with rituximab.

A 69-year-old male was referred to our hospital because of anemia, renal insufficiency, and a positive urine test for Bence-Jones protein. A bone marrow examination showed 73.7% of myeloma cells with lymphoplasmacytic morphology, the strong expressions of CD20 and CD23 by flow cytometry, and the chromosomal aberration of CCND1/IGH by FISH analysis. He was diagnosed with multiple myeloma, IgG-λ type. The initial treatment with bortezomib plus dexamethasone (BD) provided a rapid decrease in the level of IgG; however, he developed bortezomib-induced recurrent paralytic ileus accompanied by aspiration pneumonia during the second course. Interestingly, CD23 expression on myeloma cells decreased from 87.7% to 2.2% after 2 courses of BD. Negative CD23 expression was maintained following lenalidomide plus dexamethasone therapy. There are extremely few reports on CD23 expression on myeloma cells, and this is the first case report of multiple myeloma in which CD23 expression was lost after BD therapy.

Stratification of patients with multiple myeloma (MM) may be important. We investigated 138 MM patients, focusing on correlations between CD20 expression, 11 ; 14 translocation, morphology of MM cells, cyclin D1 immunostaining, and the prognosis. About 15% of patients (7/47cases) were CD20-positive, small mature MM cells, with positive cyclin D1 in the nucleus and 11; 14 translocation. Two color analysis of CD38 x CD20 antigens may be necessary to investigate CD20 expression on MM cells. Rituximab may be effective for the treatment of CD20-positive MM.