<unk><unk><unk>  (LGL) leukemia is a chronic lymphoproliferative disorder that exhibits an unexplained, chronic (> 6 months) elevation in<unk><unk>  lymphocytes (LGLs) in the peripheral blood. It is divided in two main categories: T-cell LGL leukemia (T-LGLL) and natural-killer (NK)-cell LGL leukemia (NK-LGLL). As the name suggests, T-cell<unk><unk>  lymphocyte leukemia is characterized by involvement of cytotoxic-T cells). In a study based in the US, the average age of diagnosis was 66.5 years whereas in a French study the median age at diagnosis was 59 years (with an age range of 12–87 years old). In the French study, only 26% of patients were younger than 50 years which suggests that this disorder is associated with older age at diagnosis. Due to lack of presenting symptoms, the disorder is likely to be underdiagnosed in the general population.
Large granular lymphocytic leukemia
Hemophagocytic lymphohistiocytosis
Aggressive NK-cell leukemia
Mixed-phenotype acute leukemia
T-lymphoblastic leukemia/lymphoma
Atypical chronic myeloid leukemia
Diffuse infiltrative lymphocytosis syndrome
Adult T-cell leukemia/lymphoma