SEER is an authoritative source of information on cancer incidence and survival in the United States. SEER currently collects and publishes cancer incidence and survival data from population-based cancer registries covering approximately 28 percent of the U.S. population.
Prolymphocytic leukemia is divided into two types accourding to the kind of cell involved: B-cell prolymphocytic leukemia and T-cell prolymphocytic leukemia. It is usually classified as a kind of chronic lymphocytic leukemia.
T-ALL is a neoplasm of lymphoblasts committed to the T-cell lineage, typically composed of small to medium-sized blast cells with scant cytoplasm, moderately condensed to dispersed chromatin and inconspicuous nucleoli, involving bone marrow and blood.
Most ALL patients present with widespread lymph node involvement as well as peripheral blood involvement. The number of circulating neoplastic cells does not correlate with the degree of bone marrow involvement, suggesting that circulating cells are recruited from other organs such as the skin. In fact, the skin is the most common extralymphatic site of involvement. The disease is usually systemic, involving the spleen and extranodal sites including skin, lung, liver, GI tract and CNS. Epidemiological differences occur in patterns of presentation. For example, the peripheral blood involvement is much less in patients from the Carribean basin than from Japan. Several clinical variants have been identified: acute, lymphomatous, chronic, and smoldering ATLL.
T-ALL comprises about 15% of childhood ALL. It is more common in adolescents than in younger children and more common in males than females. T-ALL comprises approximately 25% of adult ALL. Patients often present with a high leukocyte count and often a large mediastinal mass or other tissue mass. Lymphadenopathy and hepatosplenomegaly are common.