[8][9] In patients with CLL, B cell lymphocytes can begin to collect in their blood, spleen, lymph nodes, and bone marrow.

[10] Diagnosis is typically based on blood tests that find high numbers of mature lymphocytes and smudge cells.

[12] In a small number of cases, patients with CLL may present with enlarged lymph nodes, partially in areas around the neck, armpit, or groin.

[21] Autoimmune hemolytic anemia occurs in about 5-10% of CLL patients, which is when one's own immune system attacks its own red blood cells.

[23][22] These patients typically present with a sudden clinical deterioration that can be characterized by unexplained fevers or weight loss, asymmetric and rapid growth of lymph nodes, and/or a significant drop in the number of white blood cells, red blood cells, or platelets.

[22] CLL has also been reported to convert into other more aggressive diseases such as lymphoblastic lymphoma, hairy cell leukemia, high grade T cell lymphomas,[24] acute myeloid leukemia,[25] lung cancer, brain cancer, melanoma of the eye or skin,[26][27] salivary gland tumors, and Kaposi's sarcomas.

[33] Each patient with CLL may be affected by a different set of mutations, making these cells sometimes difficult to target and treat.

Of these loci, 93% are linked to the alteration of 30 gene expressions involved in immune response, cell survival, or Wnt signaling.

[33] As CLL cells accumulate, they begin to promote inflammation and an immunosuppressive environment through the release of different chemical signals.

[40][41] The diagnosis of CLL is based on the demonstration of an abnormal population of B lymphocytes in the blood, bone marrow, or tissues that display an unusual but characteristic pattern of molecules on the cell surface.

[41] The presence of lymphocytosis in a person who is elderly should raise strong suspicion for CLL, and a confirmatory diagnostic test, in particular flow cytometry should be performed unless clinically unnecessary.

If CLL-type cells are mainly found in the lymph nodes or lymphoid tissue (such as the spleen), a diagnosis of small lymphocytic lymphoma (SLL) is made.

[45] They are considered affected if a lymph node greater than 1 cm in diameter is present and/or the spleen or liver are palpable.

[48][49][50][51][52] The combination of the microscopic examination of the peripheral blood and analysis of the lymphocytes by flow cytometry to confirm clonality and molecular expression is needed to establish the diagnosis of CLL.

In practice, this is inferred by the detection of only one of the mutually exclusive antibody light chains, kappa or lambda, on the entire population of the abnormal B cells.

[62] In the past, cases with similar microscopic appearance in the blood but with a T cell phenotype were referred to as T-cell CLL.

All the B cell malignancies of the blood and bone marrow can be differentiated from one another by the combination of cellular microscopic morphology, marker molecule expression, and specific tumor-associated gene defects.

[69] Routine visits with your primary health care provider is recommended, so that they may regularly monitor your white blood cell count and watch out for the development of any signs or symptoms related to CLL.

[16] Other treatment options include: chemotherapy, radiation therapy, bone marrow transplantation, and supportive or palliative care.

[70] CLL treatment regimens vary depending on the patient's age, physical health, and progression of their disease.

[80] Younger individuals, if at high risk for dying from CLL, may consider allogeneic hematopoietic stem cell transplantation (HSCT).

[80] An intermediate level, called reduced-intensity conditioning allogeneic stem cell transplantation, may be better tolerated by older or frail patients.

[45] This system takes into account the following factors:[45] CLL is the most common type of leukemia in the Western world compared to non-Western regions such as Asia, Latin America, and Africa.

[90] In older people, however, this difference becomes less pronounced: after the age of 80 years, new cases of CLL are diagnosed equally between men and women.

[7] Because of the prolonged survival, which was typically about 10 years in past decades, but which can extend to a normal life expectancy, the prevalence (number of people living with the disease) is much higher than the incidence (new diagnoses).

In contrast, CLL is rare in Asian countries, such as Japan, China, and Korea, accounting for less than 10% of all leukemias in those regions.

[95][needs update] People who live near areas with considerable industrial pollution have an elevated risk of developing leukemia, particularly CLL.

[96] In light of newer targeted therapies such as Bruton tyrosine kinase inhibitors and anti-CD20 monoclonal antibodies, the need for bone marrow transplants in patients with CLL has become rare.

[97][98] Bone marrow transplants are only recommended in specific cases when front-line therapies have either failed and/or the patient continues to relapse.

[17] Despite the great success of these new targeted biological therapies so far, more research is needed in order to establish clearer guidelines on the optimal combination and sequence of these agents based on the patient's specific clinical presentation.