[Malignant lymphoma complicating myelodysplastic syndrome with autoantibody for the thyroid gland]

A 68 year old woman was hospitalized because of cervical lymphadenopathy. Hematological data on admission showed anemia, leukopenia with a normal platelet count. Serum serological studies revealed polyclonal hypergammaglobulinemia, a positive microsome and thyroid test, and positive reaction to antithyroglobulin antibody. Microscopic examination of a cervical lymph node revealed malignant lymphoma, diffuse large cells of B cell phenotype. The bone marrow smears revealed hypercellularity with dysplastic features including pseudo-Pelger and other nuclear abnormalities of neutrophils, micromegakaryocytes, dyserythropoiesis with megalobastic changes, 60% ring sideroblast and with no increase in proportion of blast cells (3.6%). A diagnosis of myelodysplastic syndrome (MDS, refractory anemia with ring sideroblast (RARS)) was made. Remission of ML obtained with radiation and subsequent systemic chemotherapy with CHOP-Bleo regimen, although she died 2.5 yr after the diagnosis due to relapse of ML without leukemic transformation of MDS. Although basic disturbances in these three conditions are not clear, it is evident that treatment was not concerned with the pathogenesis in this case, because the three conditions existed without treatment. It may be hypothesized that an initial event which selects a clone of stem cells that retains the capacity to differentiate into myeloid and lymphoid line would manifest with the features of RARS in the myeloid line and with the sort of immunological abnormalities reported in this case. Subsequent events select subclones and these progressively lose terminal differentiation, culminating as B-cell lymphoma.