T-cell Large Granular Lymphocyic leukemia (T-LGL)

Medium sized lymphocytes with abundant pale basophilic cytoplasm and few fine or coarse azurophilic granules. They can not be distinguished from normal reactive cytotoxic lymphocytes. Patients often present with chronic neutropenia and anemia. In healthy blood samples the number of LGL-cells comprise 10 to 15 percent of peripheral blood lymphocytes; the absolute number is 200 to 400/µL.
Secondary benign LGL expansions (non clonal) can be found in association with viral infections such as Epstein-Barr virus (EBV), hepatitis B/C virus (HBV/HCV), HIV, cytomegalovirus (CMV), connective tissue disease, immune thrombocytopenia (ITP), non-Hodgkin lymphoma, various skin disorders, and the hemophagocytosis syndrom.
By flowcytometry the cells typically show positive for CD2, CD3, CD8, CD16 and CD57; CD5 and CD7 are diminished or absent.