T cell leukemia presenting as chronic polyarthritis

T cell leukemia was detected in a woman who suffered from chronic polyarthritis. The peripheral blood leukocytes were increased in number and consisted of lymphocytes, 95% of which could be identified as T lymphocytes. T cell infiltration was found in the bone marrow, the synovial fluid, and tissue, and in nodules macroscopically resembling rheumatoid skin lesions. Further investigation of these cells by enzyme chemistry, immunohistochemistry, electron microscopy, and cytochemistry revealed that they had irregularly indented nuclei, no alpha‐naphthyl acetate esterase activity, and only faint granular acid‐phosphatase activity. The cells were negative for Ia‐like antigen and surface immunoglobulin. Analysis of the cell surface glycopeptides showed the presence of abnormally enlarged carbohydrate structures. These data suggest that these leukemic T cells are a malignant equivalent of immature T cells.