Epi-O-08 - Primary cutaneous B-cell lymphomas in children and adolescents: a SEER population-based study

Abstract

<h3>Background:</h3> The incidence of primary cutaneous B-cell lymphomas (PCBCL) in the pediatric population is unknown, and the information on pediatric PCBCL has mostly been gathered from individual case reports or series from single centers. <h3>Objective:</h3> To assess the incidence of PCBCL in the pediatric population (<20 years) compared with adult patients (≥20 years) and delineate its demographic and clinicopathologic characteristics. <h3>Methods:</h3> This was a population-based, retrospective cohort study of patients in 18 cancer registries in the United States diagnosed between 2000 to 2016 through the Surveillance, Epidemiology, and End Results (SEER) program. Age-adjusted incidence rates were calculated for PCBCL in pediatric and adult populations. Demographic, clinical, and pathological characteristics were compared between the two groups. <h3>Results:</h3> 5,128 adult and 48 pediatric PCBCL cases were included. The median age at diagnosis in the pediatric group was 16.5 years. The major histologic subtypes of pediatric cases were marginal zone lymphoma (77.1%), diffuse large B-cell lymphoma (12.5%) and follicle center lymphoma (10.4%), which significantly differed from the distribution in the adult group (p<0.001) where subtypes were equally distributed. The age-adjusted pediatric PCBCL incidence rate (per 1,000,000 person‐years) was 0.12 (95% CI 0.09-0.16) and incidence in the adult population was approximately 40-fold higher (IRR 41.4, 95% CI 31.2-56.2, P<0.001). All 48 pediatric cases were alive during a median follow-up time of 48 months. <h3>Conclusions:</h3> Pediatric PCBCL is a rare and indolent disease, which affects mostly adolescents of both sexes. Clinical presentation is similar to adults, but marginal zone subtype is significantly over-represented.