: 1441 Rai staging system (most commonly used in the United States) 
Stage 0: characterized by absolute lymphocytosis (>15,000/mm3) without lymphadenopathy, hepatosplenomegaly, anemia, or thrombocytopenia
Stage I: characterized by absolute lymphocytosis with lymphadenopathy without hepatosplenomegaly, anemia, or thrombocytopenia
Stage II: characterized by absolute lymphocytosis with either hepatomegaly or splenomegaly with or without lymphadenopathy
Stage III: characterized by absolute lymphocytosis and anemia (hemoglobin <11 g/dL) with or without lymphadenopathy, hepatomegaly, or splenomegaly
Stage IV: characterized by absolute lymphocytosis and thrombocytopenia (<100,000/mm3) with or without lymphadenopathy, hepatomegaly, splenomegaly, or anemiaBinet classification (most commonly used in Europe) 
Clinical stage A: characterized by no anemia or thrombocytopenia and fewer than three areas of lymphoid involvement (Rai stages 0, I, and II)
Clinical stage B: characterized by no anemia or thrombocytopenia with three or more areas of lymphoid involvement (Rai stages I and II)
Clinical stage C: characterized by anemia and/or thrombocytopenia regardless of the number of areas of lymphoid enlargement (Rai stages III and IV)

Array-based karyotyping
Array-based karyotyping is a cost-effective alternative to FISH for detecting chromosomal abnormalities in CLL. Several clinical validation studies have shown >95% concordance with the standard CLL FISH panel. Related diseases
In the past, cases with similar microscopic appearance in the blood but with a T cell phenotype were referred to as T-cell CLL. However, these are now recognized as a separate disease group and are currently classified as T-cell prolymphocytic leukemias (T-PLL).
While cases of PBL may present as a primary oral, or, very rarely a skin or lymph node disease, most individuals present with a widespread stage III or IV disease which in ~40% of cases, is accompanied by systemic B-symptoms such as fever, night sweats, and recent weight loss. Some 48%-63% of PBL cases occur in individuals with HIV/AIDS; ~80% of these HIV/AIDS-afflicted individuals have EBV+ disease whereas only ~50% of PBL individuals that do not have HIV/AIDS are EBV-positive. Individuals who develop PBL following organ transplantation are EBV-positive in >85% of cases. Most post-transplant and HIV/AIDS patients have an extremely aggressive disease. However, patients whose major contributing factor to PBL-development is EBV-positivity often present with, and continue to have, a significantly less aggressive disease than other patients with PBL. It is similarly clear that, on average, elderly patients (>68 years) likewise present with, and continue to have, a significantly less aggressive cancer. Pathophysiology
In addition to the immunodeficiency-causing viral disease, HIV/AIDS (which is an AIDS-defining clinical condition), recent studies have diagnosed PBL in individuals who have one or more other causes for immunodeficiency. These causes include prior organ transplantation; immunosuppressive drugs; autoimmune and chronic inflammatory diseases (e.g. hepatitis C, rheumatoid arthritis, Graves disease, Giant-cell arteritis, sarcoidosis, and severe psoriasis); and immunosenescence due to age (e.g. >60 years). Rare cases of PDL have also occurred as a transformation of a low grade B-cell malignancy such as chronic lymphocytic leukemia/small lymphocytic lymphoma and follicular lymphoma.