Large granular T lymphocytes, neutropenia and polyarthropathy: an underdiagnosed syndrome?

Thirteen patients with expansion of an unusual subset of T lymphocytes, defined by large size, cytoplasmic granularity and CD3+ CD8+ Leu 7+ surface phenotype, are reported. Although morphologically and/or phenotypically abnormal lymphocytes were found in all patients, only five had an absolute peripheral blood lymphocytosis. Ten patients had a bone marrow lymphocytosis. As in previous series, there was a strong association with neutropenia (12 patients) and polyarthropathy (seven patients). The latter group displayed a wide range of articular disease: classical or definite rheumatoid arthritis in four patients and milder non-erosive disease in the remainder. All 13 patients showed evidence of abnormal B cell function: IgM rheumatoid factor was present in nine patients, neutrophil-specific antibodies in six and all showed an increased level of at least one immunoglobulin isotype. These patients may be difficult to distinguish from those with idiopathic neutropenia and Felty's syndrome. Such a distinction may not be made on clinical grounds alone: critical assessment of lymphocyte morphology, bone marrow examination and analysis of lymphocyte phenotype should be considered in all patients with unexplained neutropenia, particularly in the context of arthritis. It is suggested that the true prevalence of this syndrome may have been greatly underestimated.