Large granular lymphocyte leukemia: case report of chronic neutropenia and rheumatoid arthritis-like symptoms in a child.

Lymphoproliferative disorders of large granular lymphocytes (LGL) are heterogeneous, with a clinical/pathologic spectrum ranging from a benign polyclonal expansion to an aggressive clonal disease. Often these lymphoproliferative disorders are associated with autoimmune disease. The clonal form of the disorder, LGL leukemia, typically occurs in older adults with a median age of 55 years at diagnosis. Pediatric cases are referred to in review articles; however, no detailed reports of T-cell LGL leukemia in children exist. This report illustrates a case of a child who presented initially at age 2 and 1/2 years with psoriasis, juvenile rheumatoid arthritis-like symptoms, and neutropenia. Bone marrow examinations obtained throughout his course have demonstrated progressive hypercellularity with increased reticulin fibers and replacement of the normal marrow elements by lymphocytes, which were later identified as large granular lymphocytes. Further testing with immunophenotyping by flow cytometry and T-cell receptor gene rearrangement studies revealed a monoclonal proliferation of large granular lymphocytes and confirmed a diagnosis of LGL leukemia. Although rare, large granular lymphocyte leukemia should be included in the differential diagnosis of chronic neutropenia in children.