B-cell prolymphocytic leukemia

B-cell prolymphocytic leukemia (B-PLL) is a rare and aggressive form of leukemia characterized by the excessive production of B-cell prolymphocytes, a type of immature white blood cell. It is a subtype of chronic lymphocytic leukemia (CLL) but is distinguished from CLL by its aggressive clinical course, distinct immunophenotypic profile, and poorer prognosis. B-PLL accounts for less than 1% of all leukemias.

Etiology and Pathogenesis

The exact cause of B-PLL is not well understood. However, it is believed to involve genetic mutations that lead to the uncontrolled growth of B-cell prolymphocytes. Chromosomal abnormalities, such as trisomy 12, deletions of 13q14, and abnormalities of 17p13, have been associated with B-PLL. These genetic changes can disrupt the normal regulation of cell growth and division, leading to leukemia.

Clinical Features

Patients with B-PLL typically present with markedly elevated white blood cell counts, splenomegaly (enlargement of the spleen), hepatomegaly (enlargement of the liver), and lymphadenopathy (swollen lymph nodes). Symptoms may include fatigue, weight loss, fever, night sweats, and frequent infections due to the suppression of the immune system by the abnormal lymphocytes.

Diagnosis

The diagnosis of B-PLL is based on the examination of peripheral blood and bone marrow. The presence of more than 55% prolymphocytes in the peripheral blood is a key diagnostic criterion. Immunophenotyping, a laboratory technique that identifies cells based on the presence of specific surface markers, is used to confirm the diagnosis. B-PLL cells typically express CD19, CD20, CD22, and CD79a, with weak expression of CD5 and CD23.

Treatment

Treatment options for B-PLL are limited and mainly consist of chemotherapy and immunotherapy. The most commonly used chemotherapeutic agents include fludarabine, cyclophosphamide, and rituximab (a monoclonal antibody targeting CD20). Allogeneic stem cell transplantation may be considered for younger patients or those with refractory disease. However, the aggressive nature of B-PLL often leads to a poor response to treatment.

Prognosis

The prognosis for patients with B-PLL is generally poor, with a median survival of less than three years. Factors that can influence prognosis include the patient's age, the presence of cytogenetic abnormalities, and the response to initial treatment.

Epidemiology

B-PLL is extremely rare, with an incidence rate that is not well defined due to its rarity. It typically affects older adults, with a median age of diagnosis around 70 years. There is a slight male predominance.

See Also

• Leukemia
• Chronic lymphocytic leukemia
• Lymphoma
• Hematology