Acquired amegakaryocytic thrombocytopenia (AATP) is a rare disease characterized by thrombocytopenia and the disappearance of marrow megakaryocytes. A 43-year-old man was admitted because of thrombocytopenia of 1.0×10 9 /L. Bone marrow aspirate demonstrated normal hematopoiesis lacking megakaryocytes, and AATP was diagnosed. The serum concentration of thrombopoietin (TPO) was high (7.72 fmol/mL). Prednisolone (PSL) at 60 mg/day was started and the platelet count recovered to 1,335×10 9 /L; however, excessive megakaryocytopoiesis and subsequent decline in platelet count were noted 14 days later. At the peak platelet count, the TPO remained at 3.79 fmol/mL and returned to a normal level of 0.40 fmol/mL during the period of normal platelet count after PSL tapering. The marked thrombocytosis in response to prednisolone may have been caused by the high TPO after the resolution of suppressed megakaryopoiesis. Marked rebound thrombocytosis beyond 1,000×10 9 /L after successful PSL treatment for AATP has not been previously reported.

Gamma-heavy chain disease (γ-HCD) is a rare B-cell tumor producing truncated IgG lacking the light chain. The clinical features of γ-HCD are heterogeneous, similar to lymphoplasmacytic lymphoma, and most patients have generalized and progressive disease. In some γ-HCD patients, autoimmune diseases are associated. Thus, γ-HCD as a restricted or indolent disease is exceptional. A 66-year-old male was referred to our hospital because of subungual hemorrhage at the bilateral halluces. Physical and laboratory examination results were nonspecific, and the hemorrhage was revealed to be traumatic. However, serum electrophoresis demonstrated a small M-peak, which was monoclonal IgG-Fc without the corresponding light chain on immunofixation and immunoelectrophoresis. Bone marrow aspirate demonstrated a small number of lymphoplasmacytic cells that were positive for CD19, CD38, CD138, and cyIgG, but negative for cyκ- and -λ light chains on flow cytometry. A diagnosis of γ-HCD was made. Chest and abdominal CT demonstrated neither hepatosplenomegaly, lymphadenopathy, nor bone lytic lesions. The serum concentrations of IgG and M-peak configuration have remained relatively unchanged for nearly 3 years. Therefore, this γ-HCD may correspond to a rare form of monoclonal gammopathy with undetermined significance.

IgA-producing lymphoplasmacytic lymphoma (LPL) is rare and IgH/c-myc translocation is rare in LPL. This is the first report of a case of IgA-producing LPL carrying t(8;14). An 86-year-old woman presented inguinal and intra-abdominal lymph node swelling, and lytic bone lesions in the lumbar vertebrae. A diagnosis of IgA-producing LPL was immunohistochemically made by inguinal lymph node biopsy. The serum IgA level was 1,180 mg/dL, which was revealed to be composed of IgA-λ monoclonal protein. Bone marrow chromosomal analysis demonstrated a complex abnormal karyotype, including t(8;14)(q24;q32), which was confirmed by FISH analysis. Abnormal lymphocytes positive for CD19, CD20, cyIgA, and cyλ were detected on flow cytometry analysis of marrow cells. Best supportive care was selected because of dementia and refractory urinary tract infection. Circulating lymphoplasmacytic cells with the same phenotype and karyotype were observed, and increased in number. The aggressive clinical course, including lytic bone lesions, may have been due to IgH/c-myc translocation or the nature of IgA-producing LPL.

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