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Lymphoma represents the third most common pediatric cancer in
children between the ages of 0 to 19 years of age.1Sixty
percent of all childhood and adolescent lymphomas are classified
as non-Hodgkin lymphoma (NHL). NHL represents approximately 8% to
10% of all malignancies that occur in children between
ages 5 to 19 years. Approximately 750 to 800 cases of NHL are diagnosed
annually in children and adolescents younger than age 20 years in
the United States. Non-Hodgkin lymphoma occurs throughout childhood
and adolescence starting as early as infancy and increasing in frequency
during adolescence with a preponderance of a 3:1 male to female
ratio. The incidence of NHL in Caucasians is approximately twice
that found in African American children with approximately 9.2 versus
4.6 cases per million.2-4 Risk factors for the development
of NHL in children and adolescents are largely unknown, except that
children with either inherited and/or acquired immunodeficiencies
have a significantly increased risk for developing NHL.
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As opposed to non-Hodgkin lymphoma (NHL) seen in adults, over
95% of childhood and adolescent NHL has been classified
to be either an intermediate or aggressive pathological subtype
by the World Health Organization (WHO) classification.5The
WHO classification, which is the most recent classification for
NHL, incorporates morphological, immunophenotypic, and molecular
characteristics to subclassify each type of lymphoma. There are
four major pathological subtypes of childhood NHL and the distribution
of these four histological subtypes include Burkitt lymphoma (BL)
(40%), diffuse large B-cell lymphoma (DLBCL) (20%),
lymphoblastic lymphoma (LL) (30%) and anaplastic large-cell
lymphoma (ALCL) (10%) (Fig. 451-1).2,3,6The
remaining (5%) of childhood NHL occurs in very rare subtypes
including some indolent B-cell lymphomas, such as follicular lymphoma
and rare T-cell subtypes including peripheral T-cell lymphoma or subtypes
of natural killer cell lymphomas.7
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Clinical Presentation, Diagnostic Evaluation,
and Staging
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The clinical manifestations of childhood and adolescent non-Hodgkin
lymphoma (NHL) depends primarily on the pathological subtype and
the primary site of involvement.2,3,7-9 Less than 10% of
childhood and adolescent NHL presents in peripheral nodal tissue;
the majority presents either in extranodal lymphoid tissue, including
the thymus or Peyer patches within the gastrointestinal tract, or manifests
in nonlymphatic tissue such as bone marrow, spinal fluid, skin,
bone, gonads, or within the central nervous system (CNS). The most
common sites of presentation include head and neck (30%),
abdomen (30%), and mediastinal and/or hilar lymph
nodes (30%). Each pathological subtype ...