Gamma-heavy chain monoclonal gammopathy with undetermined significance (MGUS).

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.

Acute monocytic leukemia diagnosed by flow cytometry includes acute myeloid leukemias with weakly or faintly positive non-specific esterase staining.

A diagnosis of acute monocytic leukemia (AML-M5) based on α-naphthyl butyrate esterase (α-NB) staining has some problems, because AML-M5 leukemic cells often show weak or faint positivity on α-NB staining. In these situations, some cases of AML-M5 tend to be misdiagnosed as AML-M0. Therefore, we evaluated the significance of weak or faint α-NB staining in AML-M5 diagnosed by flow cytometry (FCM). Nineteen AML cases in which leukemic cells were negative for naphthol AS-D chloroacetate esterase staining were studied. For FCM, we defined leukemic cells as having a monocytic nature when more than 10% of the leukemic cells were positive for at least one of the following antigens: CD4, CD11c, CD14, and CD64. The monocytic nature determined by FCM was consistent with positive or weak positivity on α-NB staining. Five of 6 cases in which leukemic cells exhibited faint positivity for α-NB staining could be diagnosed as AML-M5 by FCM, while negative α-NB staining was consistent with a diagnosis of AML-M0. These results suggest that AML-M5 should be taken into consideration even when leukemic cells are faintly positive for α-NB staining.

T-Cell Prolymphocytic Leukemia, Small Cell Variant, Possibly at the Stage of Intracytoplasmic Expression of CD3 in T-Cell Ontogenesis.

T-cell prolymphocytic leukemia, small cell variant (T-PLL-s), is a rare lymphoid neoplasm associated with a poor prognosis. We encountered a case of T-PLL-s with a characteristic phenotype. A 67-year-old female was referred to our hospital because of lymphocytosis in August 2013. Hepatosplenomegaly, lymphadenopathy, and skin lesions were absent. Hematologic examination revealed a white blood cell count of 17.9 × 10(9)/L with 81.2% mature lymphocytes, which were small with a high nuclear/cytoplasmic ratio, lacking a nucleolus and cytoplasmic granules. Anemia and thrombocytopenia were not observed. Flow cytometric analysis showed that these lymphocytes were positive for CD2, cyCD3, CD4, CD5, CD7, CD21, and CD38 (partially), but negative for smCD3, smTCR-αß and -γδ, cyTCR-ß, CD1a, CD8, CD25, HLA-DR, and terminal deoxynucleotidyl transferase. Polymerase-chain reaction analysis of cells from both the peripheral blood and the bone marrow demonstrated monoclonal rearrangement of TCR-γ. A possible rearranged band of the TCR-ß gene was observed by Southern blot analysis. The karyotype of the marrow cells was 46, XX. A diagnosis of T-PLL-s, possibly at the stage of cytoplasmic CD3 expression in the ontogenesis of T-cells, was made. The patient has been asymptomatic, and the white blood cell count has gradually increased during one-year observation, being 69.0 × 10(9)/L with 89.7% lymphocytes in August 2014.