A population-based study of pediatric anaplastic large cell lymphoma

Anaplastic large cell lymphoma (ALCL) is a relatively rare form of non-Hodgkin lymphoma (NHL) in children constituting 10-15% of this entity. To the authors' knowledge, there are no population-based pediatric studies in the literature, and incidence estimates have not been attempted.

A population-based study of all children in British Columbia, Canada, younger than 15 years of age presenting between January 1988 and December 1999 with an immunohistologically confirmed diagnosis of CD30+ ALCL was completed. Demographic, ethnic, clinical, treatment, and outcome details were collected on all patients. Population figures were obtained from census data through the BC STATS.

Ten patients were identified and confirmed to have ALCL on the basis of morphology and immunohistochemical stains. This equates to an annual incidence of 1.2 per million children younger than 15 years of age. The mean age at diagnosis was 8.23 years with a range of 1.4-13.0 years. There was an overrepresentation of East and Southeast Asian patients (40%) in the ALCL group compared with other subtypes of NHL and the pediatric population of British Columbia. Twenty percent of the patients had evidence of central nervous system (CNS) disease at diagnosis.

The annual incidence of ALCL in children younger than 15 years of age in British Columbia is 1.2 per million. The overrepresentation of East and Southeast Asian ethnic origin remains unexplained. The rate of CNS involvement is much higher than that previously reported in large non-population-based series (0-3%). Although the low numbers do not allow firm conclusions, it would seem prudent to continue to investigate all newly diagnosed patients for CNS involvement in British Columbia.